Curved Pixel-Region Image Sensor for Peripheral Autofocus
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Solution Overview
Problem
Current image sensors face challenges in achieving optimal optical and electrical characteristics, particularly in autofocus operations, where peripheral regions often remain out of focus and require manual adjustment, leading to suboptimal image quality.
Innovation Solution
The image sensor incorporates a semiconductor substrate with curved surfaces and micro-lenses, along with a pixel separation structure and photoelectric conversion regions, to split incident light into multiple beams, enabling phase difference detection and automatic focus adjustment across the entire image region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional flat semiconductor substrate is used, then the manufacturing process is simple, but the peripheral regions remain out of focus and optical characteristics deteriorate
Solution Approach 1:
The semiconductor substrate is designed with a curved surface instead of a flat surface. The curvature radius is specifically controlled to be greater than a predetermined value to ensure that light from peripheral regions can be properly focused onto the photoelectric conversion regions, thereby improving autofocus performance across the entire image sensor including peripheral areas.
Solution Approach 2:
Different regions of the semiconductor substrate have different curvature characteristics. The curved surface is designed with varying curvature radii across different regions to optimize light focusing for both central and peripheral pixel regions, enabling each region to have optimal optical characteristics for its specific function.
2Reliability
If the thickness of the semiconductor substrate is reduced to improve light focusing, then optical characteristics improve, but mechanical strength and electrical isolation between regions deteriorate
Solution Approach 1:
The thickness of the semiconductor substrate is precisely controlled within a specific range. This parameter optimization ensures that the substrate is thin enough to allow proper light focusing and transmission to the photoelectric conversion regions, while simultaneously maintaining sufficient mechanical strength and electrical isolation between adjacent pixel regions.
3Reliability
If micro-lenses are added to improve light collection, then optical efficiency improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The micro-lens array is integrated directly onto the curved semiconductor substrate in a combined structure. This merging of the micro-lens formation process with the substrate fabrication process allows for simultaneous manufacturing, reducing the number of separate fabrication steps and simplifying the overall manufacturing complexity while maintaining high light collection 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 configuration enhances autofocus capabilities, ensuring sharper images by automatically adjusting lens positions based on phase difference calculations, thereby improving image quality and reducing manual intervention.
Implementation Method 1
The semiconductor substrate includes a plurality of curved surfaces that is convex toward the plurality of micro-lenses
Implementation Method 2
a plurality of micro-lenses disposed on the semiconductor substrate and corresponding to the plurality of pixel regions
Implementation Method 3
a first photoelectric conversion region and a second photoelectric conversion region disposed in the semiconductor substrate and in each of the plurality of pixel regions
Data Source
AI summary
An image sensor includes a pixel separation structure disposed in a semiconductor substrate and defining a plurality of pixel regions, a first photoelectric conversion region and a second photoelectric conversion region disposed in the semiconductor substrate and in each of the plurality of pixel regions, and a plurality of micro-lenses disposed on the semiconductor substrate and corresponding to the plurality of pixel regions. The semiconductor substrate includes a plurality of curved surfaces that is convex toward the plurality of micro-lenses, and the semiconductor substrate has a minimum thickness between the first photoelectric conversion region and the second photoelectric conversion region in each of the plurality of pixel regions, and has a maximum thickness at a boundary between the plurality of pixel regions.