Segmented Microlens with Trenches for Image Sensor Light Collection
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Solution Overview
Problem
Conventional microlens fabrication techniques struggle to produce optimal focal characteristics for smaller image sensor pixels, leading to difficulties in achieving high color fidelity and acceptable signal-to-noise ratios due to insufficient control over microlens shaping and fabrication.
Innovation Solution
A microlens structure featuring a series of trenches with increasing cross-sectional width from the center to the edge, where the cross-sectional width of the lens material units between the trenches decreases or remains constant, providing a varying average refractive index that focuses incident light efficiently onto the photosensitive region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If microlens size is decreased to match smaller pixel photosensors, then the image sensor can be scaled down, but the control over microlens shaping and fabrication becomes insufficient
Solution Approach 1:
The microlens is segmented into multiple discrete lens elements arranged in an array, where each lens element corresponds to a pixel photosensor. This segmentation allows independent control and optimization of each microlens unit while maintaining overall system scalability.
Solution Approach 2:
The patent applies local quality by providing each microlens with specific optical properties tailored to its corresponding pixel photosensor. The lens elements can have different shapes, sizes, and refractive indices optimized for local requirements, enabling precise control over light focusing at each pixel location despite overall miniaturization.
2Productivity
If microlens size is decreased, then the image sensor array density increases, but the focal characteristics become difficult to optimize
Solution Approach 1:
The patent utilizes parameter changes by varying key optical parameters such as refractive index, lens curvature, and element spacing across the microlens array. This allows optimization of focal characteristics for each lens element while maintaining high array density, as parameters can be adjusted independently for each pixel location.
Solution Approach 2:
The microlens array employs dynamic design principles where lens elements can have varying optical properties across the array. This dynamic configuration enables each element to be optimized for its specific position and function, maintaining focal precision even as overall array density increases.
3Ease of manufacture
If conventional microlens fabrication is used, then the manufacturing process is simple, but the color fidelity and signal-to-noise ratio deteriorate
Solution Approach 1:
The patent employs composite materials by combining multiple lens elements with different optical properties within each microlens unit. This composite structure improves color fidelity and signal-to-noise ratio by utilizing materials with complementary optical characteristics, while the overall fabrication process remains compatible with standard semiconductor manufacturing techniques.
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 allows for precise control over the focal characteristics of small microlenses, enhancing light collection efficiency and maintaining high color fidelity and signal-to-noise ratios in image sensors.
Implementation Method 1
The cross-sectional width of the trenches increases in a direction from the center of the microlens to its edge while the cross-sectional width of the lens material units between the trenches decreases or remains constant in the direction from the center of the microlens to its edge. The microlens can be fabricated in a very small size and can be used in place of conventional curved lens microlens structures.
Data Source
AI summary
A microlens having a plurality of lens material units separated by a plurality of trenches and a method of forming the same is disclosed. The relationship of the trenches to the lens material is such that an average index of refraction of the microlens decreases from a center to an edge of the microlens.