Image Sensor Crosstalk Reduction via Zigzag Region Separation
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Solution Overview
Problem
As the resolution of CMOS image sensors increases, the number of pixels in a limited pixel array grows, leading to decreased pixel size and interference phenomena such as crosstalk between adjacent pixels, which affects image quality and noise levels.
Innovation Solution
The implementation of a substrate-based image sensor with a pixel separation pattern and a region separation pattern, featuring a zigzag or wavy shape, to reduce crosstalk and noise differences between adjacent unit pixels by dispersing light and preventing total reflection, thereby enhancing image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of pixels is increased to improve resolution, then image quality is improved, but crosstalk between adjacent pixels occurs due to decreased pixel size
Solution Approach 1:
The pixel array is divided into multiple unit pixels, and each unit pixel is further divided into multiple regions by region separation patterns. This segmentation isolates adjacent photoelectric conversion units, preventing crosstalk while maintaining high pixel density for improved resolution.
Solution Approach 2:
Region separation patterns act as intermediary structures between adjacent photoelectric conversion units. These patterns, with their zigzag or wavy shapes, serve as light-scattering mediators that prevent direct optical coupling between neighboring pixels, thereby eliminating crosstalk.
2Measurement precision
If the pixel size is decreased to increase the number of pixels, then resolution is improved, but interference phenomena such as crosstalk increase
Solution Approach 1:
By segmenting each unit pixel into multiple regions separated by region separation patterns, the patent prevents interference between adjacent photoelectric conversion units even when pixels are densely packed at small sizes.
Solution Approach 2:
The region separation patterns employ zigzag or wavy shapes rather than straight lines. This curvature increases the light scattering effect and surface area of the separation structure, enhancing its ability to prevent interference phenomena in high-density pixel arrangements.
3Ease of manufacture
If region separation pattern has straight shape, then manufacturing is simpler, but light scattering effect is insufficient leading to crosstalk
Solution Approach 1:
The region separation patterns use zigzag or wavy shapes instead of straight lines. This curvature significantly enhances the light scattering effect by increasing the interaction path between light and the separation pattern, effectively preventing crosstalk while remaining manufacturable through standard photolithography processes.
Solution Approach 2:
The patent optimizes parameters such as the width, depth, and wavelength of the zigzag or wavy patterns to maximize light scattering efficiency. By carefully controlling these geometric parameters, the design achieves superior crosstalk suppression without compromising manufacturability.
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
The solution effectively reduces crosstalk and noise differences between adjacent pixels, improving image quality and product reliability by dispersing light and optimizing the arrangement of photoelectric conversion units and microlenses.
Implementation Method 1
dispersing light and preventing total reflection
Data Source
AI summary
An image sensor includes a substrate. A pixel separation pattern defines a plurality of unit pixels inside the substrate. A first photoelectric conversion unit and a second photoelectric conversion unit are arranged inside each of the plurality of unit pixels in a first direction. A plurality of microlenses is disposed on the substrate to correspond to each of the plurality of unit pixels. A region separation pattern is disposed in the substrate between the first photoelectric conversion unit and the second photoelectric conversion unit. The region separation pattern extends in a second direction intersecting the first direction, is directly connected to the pixel separation pattern, and has a zigzag shape or a wavy shape in a plan view.