Semiconductor Pixel Isolation Pattern for Image Sensor Cross-Talk
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Solution Overview
Problem
Current image sensors face challenges in achieving high reliability and preventing cross-talk between pixel regions, which affects image quality and performance.
Innovation Solution
The image sensor design incorporates a pixel isolation pattern with a first semiconductor pattern and a second semiconductor pattern, where the first semiconductor pattern extends along the inner side surface of a trench and the second semiconductor pattern is vertically spaced apart from the back-side insulating layer, preventing photocharges from being diffused into neighboring pixels and reducing cross-talk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer pixel isolation pattern is used, then the manufacturing process is simple, but photocharges can diffuse into neighboring pixels causing cross-talk
Solution Approach 1:
The pixel isolation pattern is divided into two distinct semiconductor layers: a first semiconductor pattern and a second semiconductor pattern. Each layer serves as an independent barrier against photocharge diffusion, creating multiple isolation zones that collectively prevent cross-talk between adjacent pixel regions while maintaining effective charge containment.
Solution Approach 2:
The isolation structure transitions from a single-layer planar configuration to a multi-layer vertical configuration. The first semiconductor pattern is positioned at a first depth level while the second semiconductor pattern is positioned at a second depth level, creating a three-dimensional stacked isolation architecture that blocks photocharge diffusion paths in multiple spatial dimensions.
2Productivity
If pixel regions are closely spaced to increase integration density, then manufacturing cost is reduced, but cross-talk between pixels increases
Solution Approach 1:
The dual-layer semiconductor structure segments the isolation function into two distinct barriers positioned at different depths. This segmented approach creates more comprehensive isolation zones that can effectively separate closely-spaced pixel regions, enabling higher integration density while preventing photocharge leakage between adjacent pixels.
Solution Approach 2:
The first and second semiconductor patterns are nested vertically within the substrate, with each pattern positioned at a different depth level. This nested configuration creates concentric isolation zones that maximize the isolation effect within a compact vertical space, allowing pixel regions to be closely spaced horizontally while maintaining effective separation through the vertical stacking of isolation layers.
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 performance of the image sensor by preventing photocharge diffusion and reducing cross-talk between pixels, leading to improved image quality and increased integration density.
Implementation Method 1
The pixel isolation pattern penetrates the device isolation pattern and fills a first trench of the substrate... preventing photocharges from being diffused into neighboring pixels and reducing cross-talk
Data Source
AI summary
An image sensor including a substrate having first and second surfaces that are opposite to each other. The substrate includes unit pixel regions having photoelectric conversion regions. A semiconductor pattern is disposed in a first trench defined in the substrate and defines the unit pixel regions. The semiconductor pattern includes a first semiconductor pattern and a second semiconductor pattern disposed on the first semiconductor pattern. A back-side insulating layer covers the second surface of the substrate. The first semiconductor pattern includes a side portion extended along an inner side surface of the first trench and a bottom portion connected to the side portion and disposed closer to the second surface of the substrate than the side portion. The second semiconductor pattern extends toward the second surface of the substrate and is spaced apart from the back-side insulating layer with the bottom portion of the first semiconductor pattern interposed therebetween.