Image Sensor Edge Color Filter Thickness for Channel Uniformity
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Solution Overview
Problem
Current image sensors face challenges in achieving optimal optical properties, particularly in the arrangement and thickness of color filters, which can lead to channel differences and image quality issues due to varying incident angles and light transmission.
Innovation Solution
The image sensor design incorporates a semiconductor substrate with a pixel array region featuring center and edge pixel regions, where color filter groups on the edge pixel regions have varying thicknesses of color filters to ensure consistent optical paths and prevent channel differences, with micro lenses covering these filter groups to enhance light focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If color filters in edge color filter groups have the same thickness, then manufacturing is simpler, but channel differences occur and image quality deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the thickness of color filters based on their position within color filter groups. Specifically, in edge color filter groups, at least two color filters have different thicknesses compared to other color filters in the same group. This local differentiation compensates for optical path differences caused by oblique light incidence at edge regions, thereby improving image quality and reducing channel differences without requiring complete redesign of the entire sensor structure.
2Reliability
If color filters have varying thicknesses to compensate for incident angle differences, then optical properties improve, but device complexity increases
Solution Approach 1:
The patent implements local quality by applying thickness variations only to color filters in edge color filter groups, while center color filter groups maintain uniform thickness. This targeted approach improves optical performance specifically where needed (at the edges where oblique incidence occurs) without unnecessarily complicating the entire filter structure, thus balancing reliability improvement with controlled device complexity.
Solution Approach 2:
The patent segments the color filter array into center color filter groups and edge color filter groups, applying different thickness configurations to each segment. This segmentation allows the invention to optimize optical performance in edge regions without affecting the simplicity and performance of center regions, thereby improving overall optical reliability while minimizing the increase in device complexity.
3Manufacturing precision
If all color filters have uniform thickness, then manufacturing precision is easier to maintain, but channel differences cause image quality issues
Solution Approach 1:
The patent resolves this contradiction by applying local quality differentiation: color filters in edge color filter groups have varying thicknesses to compensate for oblique light incidence, while color filters in center color filter groups maintain uniform thickness. This approach ensures that manufacturing precision remains manageable in the majority of the sensor area while improving image quality and reducing channel differences in the critical edge regions.
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 properties of the image sensor by ensuring consistent light transmission and reducing channel differences, thereby enhancing image quality and performance.
Implementation Method 1
a photoelectric conversion region in the pixel array region, the photoelectric conversion region including impurities of a second conductivity type
Implementation Method 2
micro lenses covering the color filter groups, respectively
Data Source
AI summary
An image sensor includes: a semiconductor substrate including a pixel array region, the pixel array region including a center pixel region and an edge pixel region enclosing the center pixel region in a plan view; color filter groups on the pixel array region, each color filter group of the color filter groups including color filters arranged in a same number of rows and columns; and micro lenses covering the color filter groups, respectively, wherein the color filter groups include center color filter groups on the center pixel region and edge color filter groups on the edge pixel region, and at least two color filters of the color filters in each of the edge color filter groups have thicknesses that are different from each other.