Image Sensor Pixel Isolation Walls for Smaller-Pixel Cross-Talk
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Solution Overview
Problem
The reduction in pixel size of image sensors leads to electrical signal cross-talk among pixels, which adversely affects their performance, and existing manufacturing techniques struggle to minimize this issue without compromising image quality.
Innovation Solution
An image sensor design featuring an electrically non-conductive isolation structure with isolation walls that prevent signal cross-talk, comprising a photoelectric conversion layer exposing sidewalls of the isolation walls, a transparent electrode layer, an encapsulation layer, and a micro-lens layer, allowing for smaller pixel sizes without performance degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel size is reduced to increase the number of pixels per unit area, then high-resolution images can be provided, but electrical signal cross-talk among pixels occurs which adversely affects performance
Solution Approach 1:
The patent applies segmentation by dividing the semiconductor substrate into distinct pixel regions using isolation structures. These isolation structures physically separate adjacent pixels, preventing electrical signal cross-talk while maintaining high pixel density. The isolation structures create individual compartments for each pixel, ensuring that signals generated in one pixel do not interfere with adjacent pixels even as pixel size decreases.
Solution Approach 2:
The patent uses isolation structures as intermediary elements positioned between adjacent pixels. These isolation structures act as mediators that block electrical signal propagation from one pixel to another. By introducing this intermediate barrier layer, the patent successfully prevents cross-talk without requiring larger pixel spacing, thus maintaining high resolution while improving signal isolation.
2Measurement precision
If pixel size is reduced further, then higher resolution is achieved, but manufacturing challenges increase and cross-talk problems worsen
Solution Approach 1:
The patent applies preliminary action by forming isolation structures between pixels during the manufacturing process before final pixel fabrication is completed. This early establishment of isolation barriers simplifies subsequent manufacturing steps and prevents cross-talk issues from arising in the first place. By proactively creating the isolation framework, the patent reduces manufacturing complexity despite smaller pixel dimensions.
3Reliability
If isolation structures are added to prevent cross-talk, then signal isolation is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by implementing isolation structures only in the specific regions where cross-talk prevention is needed - namely, between adjacent pixels. Rather than complicating the entire device architecture, the isolation structures are locally applied at pixel boundaries. This targeted approach provides effective signal isolation while minimizing overall device complexity and maintaining simplicity in other portions of the sensor structure.
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
The solution effectively prevents electron/hole cross-talk among pixels, enabling the production of high-resolution image sensors with smaller pixel sizes without compromising performance, by using an isolation structure that controls the shape and refractive index of the isolation walls to manage signal passage.
Implementation Method 1
signal electric charges may be generated according to the amount of light received by the light-sensing portion
Data Source
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Figure 1B
Figure 1C
AI summary
An image sensor is provided. The image sensor includes a substrate, an isolation structure on the substrate, a photoelectric conversion layer, a transparent electrode layer, an encapsulation layer, a color filter layer, and a micro-lens. The isolation structure is electrically non-conductive and defines a plurality of pixel regions on the substrate. The isolation structure prevents cross-talk of electrical signals among pixels. The photoelectric conversion layer is disposed on the pixel regions defined by the isolation structure. The transparent electrode layer is disposed over the isolation structure and the photoelectric conversion layer. The encapsulation layer is disposed over the transparent electrode layer. The micro-lens is disposed on the color filter layer.