CMOS Image Sensor Pixel Isolation With AR-Layer Capping
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Solution Overview
Problem
Current CMOS image sensors face challenges in reliability and yield due to issues with pixel isolation and antireflection layers, leading to inefficiencies in light conversion and signal processing.
Innovation Solution
The proposed solution involves a CMOS image sensor design with a substrate having a pixel isolation part that includes semiconductor patterns penetrating the substrate, dielectric patterns, and a capping pattern in contact with the antireflection layer, which enhances pixel separation and protects against debris, thereby improving reliability and yield during fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pixel isolation structure is used, then the fabrication process is simple, but the reliability and yield are reduced due to debris contamination and poor pixel separation
Solution Approach 1:
The pixel isolation structure is segmented into multiple functional layers: a first isolation dielectric layer for primary isolation, a semiconductor pattern for structural support and additional isolation, and a capping pattern for protection. This segmentation allows each layer to perform its specific function optimally, improving reliability while managing complexity through modular design.
Solution Approach 2:
The first isolation dielectric layer is formed in advance before the semiconductor pattern and capping pattern are added. This preliminary action ensures that the isolation function is established early in the fabrication process, preventing debris contamination from the outset and improving yield without requiring complex post-processing steps.
2Productivity
If the pixel isolation part does not protect against fabrication debris, then the structure is simpler, but the yield is reduced due to contamination
Solution Approach 1:
The capping pattern is deposited over the semiconductor pattern and first isolation dielectric layer to provide protective cushioning against fabrication debris and contaminants. This protective layer prevents contamination during subsequent fabrication steps, thereby improving yield without significantly increasing process complexity.
3Reliability
If the semiconductor pattern does not penetrate the substrate, then the fabrication process is simpler, but the pixel separation and isolation effectiveness are reduced
Solution Approach 1:
The semiconductor pattern is selectively formed to penetrate the substrate only in regions where enhanced isolation is needed, while maintaining a simpler structure in other areas. This local quality approach improves pixel separation effectiveness at critical interfaces without unnecessarily complicating the entire fabrication 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 reliability and yield of the image sensor by effectively isolating pixels and protecting against fabrication debris, leading to improved light conversion and signal processing capabilities.
Implementation Method 1
The photodiode serves to transform an incident light into an electrical signal
Data Source
AI summary
Disclosed is an image sensor and a fabrication method. The image sensor comprises a substrate having a first surface and a second surface that are opposite to each other, an antireflection layer on the second surface of the substrate, and a pixel isolation part in the substrate and separating a plurality of pixels from each other. The pixels include first to fourth pixels. The pixel isolation part includes a first part between the first pixel and the third pixel and a second part between the first pixel and the second pixel. Each of the first part and the second part includes a semiconductor pattern that penetrates the substrate along a direction perpendicular to the first surface, a first isolation dielectric pattern between the substrate and the semiconductor pattern, and a capping pattern in the semiconductor pattern. The capping pattern is in contact with the antireflection layer.