Image Sensor Pixel Isolation and Separation Structures
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Solution Overview
Problem
Current image sensors face challenges in achieving optimal optical and electrical characteristics, particularly in auto-focusing applications, due to limitations in pixel isolation and light separation structures, which affect the accuracy and efficiency of light sensing and signal processing.
Innovation Solution
The image sensor design incorporates a semiconductor substrate with distinct pixel group regions, each equipped with photoelectric conversion regions and separation structures, including pixel isolation and separation structures, to effectively separate and process different light sources, enhancing light sensitivity and reducing cross-talk between pixel regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pixel isolation structures are used to separate pixel regions, then cross-talk between pixel regions is reduced, but manufacturing complexity increases
Solution Approach 1:
The pixel array is divided into first and second pixel groups with different photoelectric conversion characteristics. Each pixel group is further segmented into multiple pixel regions separated by pixel isolation structures. This segmentation allows independent optimization of each region while maintaining overall system functionality, reducing cross-talk through physical separation.
Solution Approach 2:
Different pixel regions are assigned different photoelectric conversion characteristics (e.g., different spectral responses or conversion efficiencies) to optimize performance for specific applications. The pixel isolation structures are strategically placed at locations where cross-talk is most problematic, rather than uniformly across the entire array, reducing manufacturing complexity while maintaining effectiveness.
2Measurement precision
If separation structures are added between photoelectric conversion regions, then light sensing accuracy is improved, but device complexity increases
Solution Approach 1:
Each pixel region containing multiple photoelectric conversion regions is further divided by separation structures. This segmentation isolates the optical paths and electrical signals from different conversion regions, preventing signal interference and improving measurement precision for dual-conversion applications.
Solution Approach 2:
Separation structures act as intermediary elements between adjacent photoelectric conversion regions. These structures provide both optical isolation (blocking stray light) and electrical isolation (preventing charge carrier diffusion), thereby improving sensing accuracy without requiring complete physical separation of the conversion regions.
3Reliability
If multiple pixel groups with different light sensing capabilities are integrated, then auto-focusing performance is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The pixel array is segmented into multiple pixel groups, each with specialized photoelectric conversion characteristics optimized for different wavelengths or focusing functions. This segmentation allows independent fabrication and testing of each group before integration, reducing the overall manufacturing precision burden while maintaining high auto-focusing performance.
Solution Approach 2:
The pixel isolation structures and separation structures serve multiple functions simultaneously: they provide mechanical support, electrical isolation, optical isolation, and signal routing. This multi-functionality reduces the number of separate components needed, simplifying the manufacturing process and reducing alignment precision requirements despite the complex functionality.
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 improves the optical and electrical characteristics of the image sensor, leading to enhanced auto-focusing capabilities and increased signal differentiation, thereby improving the overall performance and accuracy of light sensing operations.
Implementation Method 1
first and second photoelectric conversion regions disposed in each of the first and second pixel regions of the semiconductor substrate
Data Source
AI summary
An image sensor is disclosed. The image sensor may include a semiconductor substrate including a first pixel group region and a second pixel group region, the first pixel group region including first pixel regions to sense a first light, the second pixel group region including second pixel regions to sense a second light, each of the first and second pixel regions arranged in n columns and m rows, a pixel isolation structure disposed in the semiconductor substrate to separate the first and second pixel regions from each other, first and second photoelectric conversion regions disposed in each of the first and second pixel regions of the semiconductor substrate, and a first separation structure disposed in each of the first pixel regions and in the semiconductor substrate between the first and second photoelectric conversion regions. The first separation structure may be spaced apart from the pixel isolation structure.