Image Sensor Isolation Structures for Cross-Talk Reduction
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Solution Overview
Problem
Current image sensors face challenges in achieving high performance and efficient auto-focusing due to limitations in optical characteristics and isolation structures, leading to issues with cross-talk and noise levels between pixel regions.
Innovation Solution
The image sensor design incorporates a semiconductor substrate with specific pixel regions and isolation structures, including insulating layers and impurity regions, arranged in orthogonal directions to reduce cross-talk and improve auto-focusing capabilities, using different refractive indices and shapes for isolation structures to manage light and noise effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If uniform isolation structures are used across all pixel regions, then manufacturing simplicity is maintained, but cross-talk between different types of pixel regions cannot be effectively minimized
Solution Approach 1:
The patent applies different isolation structure configurations to different pixel regions: first isolation structures (with first refractive index) are used in first pixel regions, while second isolation structures (with second refractive index different from the first) are used in second pixel regions. This local differentiation optimizes optical isolation for each region's specific requirements, effectively minimizing cross-talk between adjacent pixel regions of different types.
Solution Approach 2:
The isolation structures are segmented into distinct types corresponding to different pixel region types. The semiconductor substrate is divided into first pixel regions and second pixel regions, each with dedicated isolation structures tailored to their optical characteristics, allowing optimized isolation performance across the entire sensor array.
2Reliability
If different refractive indices are used for isolation structures in different pixel regions, then optical characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
Different refractive indices are assigned to isolation structures based on their location: first isolation structures in first pixel regions have a first refractive index, while second isolation structures in second pixel regions have a second refractive index. This local optimization improves optical characteristics by reducing light scattering and cross-talk specific to each region's function.
Solution Approach 2:
The refractive index parameter of the isolation structures is changed according to the pixel region type. By varying this optical parameter locally, the patent optimizes light propagation and isolation characteristics for different pixel functions while maintaining a relatively simple overall manufacturing process.
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 design enhances the image sensor's optical characteristics, reduces noise levels, and improves auto-focusing performance by minimizing cross-talk between pixel regions, resulting in improved image quality and functionality.
Implementation Method 1
respective first isolation structures are disposed in the semiconductor substrate between the first and second photoelectric conversion devices in respective ones of the first pixel regions and respective second isolation structures are disposed in the semiconductor substrate between the first and second photoelectric conversion devices in respective ones of the second pixel regions, the second isolation structures being different from the first isolation structures in terms of their refractive indices
Data Source
AI summary
An image sensor includes a semiconductor substrate, a first pair of photoelectric conversion regions in a first pixel region of the substrate and a first isolation structure between the photoelectric conversion regions of the first pair of photoelectric conversion regions. The sensor further includes a second pair of photoelectric conversion regions in a second pixel region of the substrate adjacent the first pixel region and a second isolation structure between the photoelectric conversion regions of the second pair of photoelectric conversion regions and having different optical properties than the first isolation structure. First and second different color filters (e.g., green and red) may be disposed on respective ones of the first and second pixel regions.