Dual-Material Deep Isolation in Image Sensors for Cross-Talk Control
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Solution Overview
Problem
Image sensors face challenges in preventing cross-talk and minimizing noise, which affect their performance in capturing clear images.
Innovation Solution
The image sensor design incorporates a deep device isolation pattern with a semiconductor pattern penetrating the substrate and an isolation pattern using different materials, such as a low refractive index material adjacent to the incident light surface and a high-k material adjacent to the other surface, to prevent cross-talk and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-material isolation pattern is used in the deep device isolation pattern, then the structure is simple and easy to manufacture, but cross-talk between pixel regions cannot be effectively prevented and noise is not minimized
Solution Approach 1:
The isolation pattern in the deep device isolation pattern is formed using a composite structure of two different insulating materials: a first insulating material (e.g., silicon oxide) and a second insulating material (e.g., silicon nitride). This composite material approach enables effective cross-talk prevention and noise minimization by combining the properties of different materials, while the pattern is formed in a single etching process step that maintains manufacturing simplicity.
2Reliability
If the deep device isolation pattern penetrates the entire substrate, then cross-talk prevention is maximized, but manufacturing complexity and process difficulty increase
Solution Approach 1:
The deep device isolation pattern penetrates only a portion of the substrate thickness rather than the entire substrate. The isolation pattern extends from the first surface to a depth that is less than the full substrate thickness, which is sufficient to prevent cross-talk between pixel regions while avoiding the manufacturing complexity and process difficulties associated with complete substrate penetration.
3Reliability
If different materials are used in the first and second isolation patterns, then cross-talk and noise are effectively minimized, but the manufacturing process becomes more complex
Solution Approach 1:
The isolation pattern is segmented into two distinct regions: a first isolation pattern formed with a first insulating material and a second isolation pattern formed with a second insulating material. This segmentation allows each material to be optimized for specific functions (e.g., one material for cross-talk prevention, another for noise minimization) while both patterns are formed in a single etching process step that maintains manufacturing efficiency.
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 minimizes cross-talk and noise, enhancing the signal-to-noise ratio and improving image quality by ensuring that incident light is efficiently captured without interference between pixel regions.
Implementation Method 1
a first isolation pattern adjacent to the second surface of the substrate and comprising a low refractive index material
Implementation Method 2
a first isolation pattern adjacent to the second surface of the substrate and comprising a low refractive index material, wherein the second surface of the substrate is a surface through which incident light is incident to a pixel region
Implementation Method 3
a second isolation pattern adjacent to the first surface of the substrate and comprising a second insulating material different from the first insulating material
Data Source
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AI summary
An image sensor includes a substrate including pixel regions and having a first surface, a second surface opposite the first surface, and a first trench recessed from the first surface, a shallow device isolation pattern provided in the first trench, and a deep device isolation pattern between the pixel regions and provided in the substrate. The deep device isolation pattern includes a semiconductor pattern penetrating at least a portion of the substrate, and an isolation pattern provided between the substrate and the semiconductor pattern. The isolation pattern includes a first isolation pattern adjacent to the second surface, and a second isolation pattern adjacent to the first surface. A first interface at which the first isolation pattern contacts the second isolation pattern is spaced apart from the shallow device isolation pattern. The first isolation pattern includes a different material from that of the second isolation pattern.