Nested Pixel Isolation Layout for Small-Pixel Image Sensors
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Solution Overview
Problem
Current image sensors face challenges in effectively isolating subpixels, leading to issues such as dark current generation and blooming effects, which affect image quality and resolution.
Innovation Solution
The implementation of a pixel isolation structure comprising an outer isolation layer, isolation layer connection portions, inner isolation layers, an isolation liner, and isolation pillars that surround and separate subpixels, reducing dark current and blooming by controlling the size and separation of subpixel regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel size is reduced to increase resolution, then image resolution is improved, but dark current and blooming effects worsen
Solution Approach 1:
The pixel isolation structure is divided into multiple components: outer isolation layer, inner isolation layer, isolation liner, and isolation pillar. Each component serves a specific isolation function at different spatial scales, collectively suppressing dark current and blooming effects while maintaining small pixel dimensions for high resolution
Solution Approach 2:
The isolation structure employs a nested configuration where the isolation liner is positioned within the inner isolation layer, which is in turn surrounded by the outer isolation layer, with the isolation pillar providing additional containment. This multi-layer nested structure achieves comprehensive isolation in a compact footprint, enabling high resolution without compromising isolation performance
2Device complexity
If isolation structure is simplified to reduce manufacturing complexity, then device complexity is reduced, but isolation effectiveness deteriorates
Solution Approach 1:
The isolation function is segmented across four distinct structural components, each with specific geometric characteristics and positioning. This segmentation allows each component to be optimized for its specific isolation role while collectively achieving comprehensive suppression of dark current and blooming effects
Solution Approach 2:
The outer isolation layer, inner isolation layer, isolation liner, and isolation pillar are combined into an integrated pixel isolation structure that works synergistically. The combination of these components creates a unified isolation system that maintains reliability while being manufacturable through standardized semiconductor fabrication processes
Data Source
AI summary
An image sensor including a color pixel including a plurality of subpixels arranged in an m×n matrix, and each of m and n is a natural number of 2 to 10, on a substrate, and a pixel isolation structure configured to isolate each of the plurality of subpixels in the color pixel, wherein the pixel isolation structure includes, an outer isolation layer surrounding the color pixel, at least one isolation layer connection portion extending in a center direction of the color pixel from an inner wall of the outer isolation layer, at least one inner isolation layer limiting a size of a partial region of each of the plurality of subpixels in a region limited by the outer isolation layer, including a part between two subpixels adjacent to each other among the plurality of subpixels.