Deep Device Isolation Pattern for CMOS Image Sensor Cross-Talk Reduction
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Solution Overview
Problem
Current CMOS image sensors face challenges in reducing cross-talk between adjacent pixel regions, leading to inefficiencies in light conversion and signal processing.
Innovation Solution
The implementation of a deep device isolation pattern with semiconductor and insulating structures, including sidewall portions and a filling portion, is used to prevent cross-talk between pixel regions, enhancing the isolation and efficiency of light conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a deep device isolation pattern is implemented to reduce cross-talk between pixel regions, then optical efficiency is improved, but device complexity increases due to the multi-component structure including semiconductor patterns, sidewall insulating patterns, and filling portions
Solution Approach 1:
The deep device isolation pattern is segmented into multiple functional components: semiconductor patterns extending from the second surface, sidewall insulating patterns covering the semiconductor pattern sidewalls, and filling portions completing the isolation structure. This segmentation allows each component to perform its specific function optimally while collectively achieving superior cross-talk reduction between adjacent pixel regions.
Solution Approach 2:
The isolation structure employs a nested configuration where the semiconductor pattern is positioned at the core, the sidewall insulating pattern is nested around the semiconductor pattern's sidewalls, and the filling portion is nested within the remaining space. This nested doll approach maximizes space utilization and ensures complete isolation while maintaining a compact deep trench structure.
2Reliability
If the semiconductor pattern top surface is positioned higher than the filling portion top surface, then light reflection efficiency is improved, but manufacturing precision requirements increase due to the height differential
Solution Approach 1:
The semiconductor pattern is designed with local quality variations where the top surface is positioned at a higher elevation than the filling portion top surface. This localized height difference creates an optimal light reflection interface that enhances optical efficiency by directing reflected light away from adjacent pixel regions, while the surrounding structures maintain their respective functions.
Solution Approach 2:
The solution transitions from a two-dimensional planar isolation approach to a three-dimensional vertical structure by positioning the semiconductor pattern top surface at a different height than the filling portion. This dimensional change enables enhanced light reflection control in the vertical dimension, creating an optical path that improves cross-talk reduction while managing manufacturing precision through structured layering.
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 cross-talk and improves the optical efficiency of the image sensor by increasing the total reflection efficiency and preventing issues like white spots and dark currents.
Implementation Method 1
Each of the pixels may include a photodiode (PD) that coverts it light into an electrical signal
Implementation Method 2
This solution effectively reduces cross-talk and improves the optical efficiency of the image sensor by increasing the total reflection efficiency
Data Source
AI summary
An image sensor includes: a substrate including a plurality of pixel regions, a first surface and a second surface opposite to the first surface; and a deep device isolation pattern disposed between adjacent pixel regioas of the phirality of pixel regions and penetrating the substrate, wherein the deep deice isolation pattern includes: a semiconductor pattern extended from the second surface toward the first surface; and sidewall insulating patterns interposed between the semiconductor pattern and the substrate, wherein the semiconductor pattern includes sidewall portions and a filling portion, wherein the sidewall portions are provided adjacent to the sidewall insulating patterns, respectively, wherein the filling portion is provided between the sidewall portions, and wherein top surfaces of the sidewall portions are located at a height higher than a top surface of the filling portion,