Image Sensor Floating Diffusion Connector for Lower Parasitic Capacitance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing image sensor technologies face challenges in efficiently connecting floating diffusion regions, leading to increased capacitive coupling and reduced freedom in wire routing due to the lack of effective isolation structures.
Innovation Solution
The implementation of a shallow trench isolation structure with a floating diffusion region connector buried within it, which connects multiple floating diffusion regions and reduces capacitive coupling by having an upper surface lower than the isolation structure, allowing for increased wire routing flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If floating diffusion regions are connected using conventional routing methods, then electrical connection is achieved, but parasitic capacitance increases and wire routing freedom is reduced
Solution Approach 1:
A dedicated floating diffusion region connector is introduced as an intermediary structure between floating diffusion regions. This connector is specifically designed to provide electrical connection while minimizing parasitic capacitance through its geometric configuration and material properties, thereby resolving the contradiction between achieving reliable electrical connection and reducing harmful parasitic effects.
Solution Approach 2:
The connector's dimensions, shape, and material composition are optimized to change key electrical parameters. By adjusting the connector's width, length, and depth ratios, the parasitic capacitance is minimized while maintaining adequate electrical connection. This parameter optimization allows simultaneous achievement of reliable connection and reduced parasitic effects.
2Reliability
If conventional connection structures are used, then floating diffusion regions are connected, but wire routing flexibility is reduced due to lack of isolation
Solution Approach 1:
The connection structure is segmented into distinct functional zones: isolation regions with higher dielectric constant materials, connector regions with optimized geometry, and transition zones. This segmentation allows independent optimization of each zone for its specific function, enabling both reliable connection and flexible wire routing by confining electrical fields to specific regions.
Solution Approach 2:
Different regions of the connection structure have different local properties - isolation regions use high-k dielectric materials to confine fields, while connector regions use low-capacitance geometries. This local quality variation allows the structure to simultaneously provide reliable electrical connection in the connector region and isolation for wire routing freedom in the isolation regions.
3Object-affected harmful factors
If floating diffusion regions are isolated to reduce parasitic capacitance, then capacitive coupling is reduced, but connection complexity increases
Solution Approach 1:
The floating diffusion region connector serves multiple functions simultaneously: it provides electrical connection between floating diffusion regions, acts as an isolation structure to reduce parasitic capacitance, and enables flexible wire routing. This multi-functionality reduces overall device complexity by consolidating what would otherwise require separate structures for each function.
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 effectively reduces parasitic capacitance and enhances the freedom of wire disposition, improving the overall performance and efficiency of the image sensor by minimizing capacitive coupling and allowing for more flexible wire routing.
Implementation Method 1
reduces parasitic capacitance and enhances the freedom of wire disposition, improving the overall performance and efficiency of the image sensor by minimizing capacitive coupling
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An image sensor (500) includes a first substrate (1) having a first side (1a) and a second side (1b) opposite each other, and including a pixel array region (APS) having plurality of active regions (ACT) disposed at the first side (1a), a shallow trench isolation structure (STI) disposed at the first side (1a) of the first substrate (1) and isolating each of the plurality of active regions (ACT), a plurality of floating diffusion regions (FD) disposed at the plurality of active regions of the first substrate (1), and a floating diffusion region connector (19) connecting the plurality of floating diffusion regions (FD) with each other. The floating diffusion region connector (19) is buried in the shallow trench isolation structure (STI) and an upper surface of the floating diffusion region connector (19) is lower than an upper surface of the shallow trench isolation structure (STI).