Pixel Isolation Structure Layout for Lower Dark Current Sensors
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Solution Overview
Problem
Image sensors face challenges in minimizing dark current and enhancing optical property efficiency and sensitivity, particularly in achieving high resolution and miniaturization.
Innovation Solution
The image sensor design incorporates a second chip structure with an isolation structure that includes gap-fill patterns and isolation layers surrounding photoelectric conversion device regions, which reduces dark current and improves optical efficiency by locally disposing gap-fill patterns adjacent to corners of the photoelectric conversion device regions, allowing for better light absorption and electrical connection for negative voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If isolation structures are added to reduce dark current, then dark current properties are improved, but device complexity increases
Solution Approach 1:
The isolation structure is divided into multiple functional layers: first isolation layers surrounding photoelectric conversion device regions, second isolation layers surrounding the first isolation layers, and gap-fill patterns in specific regions. This segmentation allows each layer to perform its specific function in reducing dark current while maintaining overall structural organization and manageability.
Solution Approach 2:
Gap-fill patterns are selectively placed only in first regions adjacent to side surfaces of photoelectric conversion device regions, not uniformly across all areas. This local placement strategy reduces unnecessary material usage and structural complexity while maintaining effective dark current suppression where it is most needed.
2Reliability
If gap-fill patterns are placed adjacent to corners of photoelectric conversion device regions, then optical property efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The space around photoelectric conversion device regions is divided into different zones: first regions adjacent to side surfaces and second regions adjacent to corners. Gap-fill patterns are placed only in first regions, creating a clear spatial segmentation that simplifies manufacturing alignment requirements while maintaining optical efficiency.
Solution Approach 2:
The first isolation layers serve as intermediary structures that define the boundaries for gap-fill pattern placement. These isolation layers act as reference structures that simplify the positioning process for gap-fill patterns, reducing the direct precision requirements between gap-fill patterns and photoelectric conversion device regions.
3Reliability
If multiple isolation layers and gap-fill patterns are implemented, then sensitivity is improved, but ease of manufacture decreases
Solution Approach 1:
The isolation structure is segmented into standardizable components (first isolation layers, second isolation layers, gap-fill patterns) that can be manufactured using sequential deposition and etching processes. Each component can be processed independently using standard semiconductor manufacturing techniques, making the complex structure easier to manufacture.
Solution Approach 2:
The isolation layers serve multiple functions: they provide electrical isolation, define structural boundaries, and serve as reference structures for subsequent gap-fill pattern placement. This multi-functionality reduces the need for additional dedicated structures, simplifying the overall manufacturing 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 effectively reduces dark current, enhancing image sensor performance by improving optical property efficiency and sensitivity, leading to better image generation capabilities.
Implementation Method 1
an isolation structure in the second substrate... first isolation layers surrounding the photoelectric conversion device regions, respectively, second isolation layers surrounding the first isolation layers
Implementation Method 2
microlenses on the color filters
Implementation Method 3
color filters on the anti-reflective layers
Implementation Method 4
photoelectric conversion device regions spaced apart from each other by the isolation structure in the second substrate
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
An image sensor (1000) includes photoelectric conversion device regions (PD) in a substrate; and an isolation structure (IS) extending in a direction from a first surface of the substrate to a second surface opposing the first surface, surrounding the photoelectric conversion device regions (PD) in a plan view, and having first regions (LR) adjacent to side surfaces of the photoelectric conversion device regions (PD) and second regions (CR) adjacent to each corner of the photoelectric conversion device regions (PD). The isolation structure (IS) includes first isolation layers (251) surrounding the photoelectric conversion device regions (PD), respectively, second isolation layers (252) surrounding the first isolation layers (251), first gap-fill patterns filling at least a portion of a space between the second isolation layers (252) in the first regions (LR), and second gap-fill patterns filling at least a portion of a space between the second isolation layers (252) in the second regions (CR), in the plan view.