Pixel Isolation Layout for Autofocus Image Sensor Crosstalk
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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 separation structures, which affect signal quality and cross-talk between photoelectric conversion regions.
Innovation Solution
The image sensor incorporates a pixel isolation structure and separation structures in a semiconductor substrate to define pixel regions, with specific configurations of pixel isolation portions and separation structures that prevent cross-talk and enhance signal differentiation, allowing for improved auto-focusing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If pixel isolation structures are used to define pixel regions, then cross-talk between regions is reduced, but device complexity increases
Solution Approach 1:
The pixel isolation structure is segmented into first pixel isolation portions extending in a first direction and second pixel isolation portions extending in a second direction, creating a grid-like pattern that effectively divides the semiconductor substrate into discrete pixel regions while managing complexity through systematic segmentation
Solution Approach 2:
The separation structure is positioned at specific locations between photoelectric conversion regions within pixel regions, providing localized cross-talk prevention where it is most needed rather than uniform isolation throughout the entire device, thus reducing overall device complexity
2Measurement precision
If separation structures are added between photoelectric conversion regions, then signal differentiation is improved, but manufacturing complexity increases
Solution Approach 1:
The separation structure is integrated with the pixel isolation structure, where the separation structure extends between photoelectric conversion regions and connects to or is formed as part of the pixel isolation portions, combining multiple functions into a single manufactured element to reduce manufacturing complexity
Solution Approach 2:
The pixel isolation portions serve dual functions: they define pixel region boundaries and simultaneously act as separation structures between photoelectric conversion regions, eliminating the need for separate dedicated separation elements and simplifying the 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
The solution effectively reduces cross-talk between pixel regions, increases signal differentiation, and enhances the auto-focusing operation by ensuring better light management and signal quality, thereby improving the overall performance of the image sensor.
Implementation Method 1
a pixel isolation structure disposed in a semiconductor substrate to define a first pixel region, first and second photoelectric conversion regions disposed in the first pixel region, and a separation structure disposed in the first pixel region, between the first and second photoelectric conversion regions
Implementation Method 2
first and second photoelectric conversion regions disposed in the first pixel region
Data Source
AI summary
An image sensor may include a pixel isolation structure disposed in a semiconductor substrate to define a first pixel region, first and second photoelectric conversion regions disposed in the first pixel region, and a separation structure disposed in the first pixel region, between the first and second photoelectric conversion regions. The pixel isolation structure may include first pixel isolation portions, which are spaced apart from each other in a second direction and extend lengthwise in a first direction, and second pixel isolation portions, which are spaced apart from each other in the first direction and extend lengthwise in the second direction to connect to the first pixel isolation portions. The separation structure may be spaced apart from the pixel isolation structure in the first direction and the second direction, and is at least partly at the same level as the first and second photoelectric conversion regions in a third direction perpendicular to the first direction and the second direction.