Pixel Separation Structure for Image Sensor Crosstalk Control
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Solution Overview
Problem
As image sensors with increased integration levels experience reduced pixel sizes, they face issues of crosstalk and dark current due to misalignment during the contact formation process, which complicates the manufacturing and affects their performance.
Innovation Solution
The implementation of a substrate with pixel regions and dummy pixel regions, along with a pixel separation structure and a dummy pixel separation structure, using conductive and insulating layers to reduce crosstalk and dark current, and a pixel separation contact disposed on the dummy pixel separation structure to stabilize electrical connections and prevent misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the degree of integration of the image sensor is increased, then the size of each pixel region is reduced, but crosstalk from adjacent pixel regions occurs and dark current is generated
Solution Approach 1:
The pixel separation structure divides the substrate into isolated pixel regions using conductive layers and insulating layers, creating physical and electrical segmentation that prevents crosstalk between adjacent pixels while maintaining high integration density
Solution Approach 2:
The pixel separation structure acts as an intermediary element between adjacent pixel regions, using conductive layers to control potential distribution and insulating layers to provide electrical isolation, thereby eliminating crosstalk and reducing dark current generation
2Productivity
If the size of each pixel region is reduced, then integration level increases, but misalignment during contact formation process occurs
Solution Approach 1:
The pixel separation structure is formed preliminarily before contact formation, establishing a predefined alignment reference that guides subsequent contact formation processes and prevents misalignment issues
Solution Approach 2:
The pixel separation structure replicates the pixel array pattern, creating a corresponding reference structure that ensures accurate alignment during contact formation by matching the geometric arrangement of pixel regions
3Object-affected harmful factors
If pixel separation structure is formed to reduce crosstalk, then manufacturing complexity increases, but process simplification is needed
Solution Approach 1:
The pixel separation structure combines multiple functions into a single integrated structure: conductive layers for potential control, insulating layers for electrical isolation, and geometric patterns for alignment reference, thereby reducing the number of separate manufacturing steps
Solution Approach 2:
The pixel separation structure serves multiple purposes simultaneously: it provides electrical isolation between pixels, controls potential distribution to prevent crosstalk, and acts as an alignment reference for contact formation, eliminating the need for separate structures for each function
Data Source
AI summary
An image sensor includes a substrate including a plurality of pixel regions and one or more pairs of dummy pixel regions; a pixel separation structure between two adjacent pixel regions among the plurality of pixel regions and including a first conductive layer; a dummy pixel separation structure between the one or more pairs of dummy pixel regions, electrically connected to the pixel separation structure, and including a second conductive layer; and a pixel separation contact disposed on the dummy pixel separation structure.