Phase Detection Pixel Microlens Height Tuning for Autofocus Accuracy
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Solution Overview
Problem
Conventional image sensor manufacturing processes produce micro-lenses for different pixels using the same process conditions, resulting in suboptimal curvature and performance characteristics, such as separation ratio and signal-to-noise ratios, due to uniform lens production.
Innovation Solution
The image sensor design involves forming micro-lenses of different heights and curvatures for image sensing and phase detection pixels using distinct processes, allowing for independent optimization of pixel characteristics and enhanced separation ratio characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If micro-lenses are produced using the same manufacturing process for all pixels, then manufacturing simplicity is maintained, but lens optimization and performance characteristics deteriorate
Solution Approach 1:
The patent applies local quality by forming micro-lenses with different heights and curvatures tailored to specific pixel types. Image sensing pixels receive micro-lenses with first heights optimized for light gathering, while phase detection pixels receive micro-lenses with second heights optimized for phase difference measurement. This localized customization resolves the contradiction by maintaining a unified manufacturing process while achieving pixel-specific optimization through selective parameter adjustment.
2Manufacturing precision
If micro-lenses of different heights are formed for different pixel types, then lens optimization and performance improve, but manufacturing complexity increases
Solution Approach 1:
The patent implements parameter changes by modifying the height and curvature parameters of micro-lenses based on pixel type requirements. During the manufacturing process, different etch depths or deposition conditions are applied to create micro-lenses with first heights for image sensing pixels and second heights for phase detection pixels. This approach enables performance optimization while managing manufacturing complexity through controlled parameter variation rather than fundamentally changing the manufacturing process.
3Stability of the object's composition
If uniform micro-lenses are produced for all pixels, then manufacturing consistency is maintained, but auto-focusing performance and separation ratio deteriorate
Solution Approach 1:
The patent resolves this contradiction by applying local quality principles where micro-lenses are customized according to their functional requirements. Image sensing pixels utilize micro-lenses with first heights optimized for general light capture and color filtering, while phase detection pixels utilize micro-lenses with second heights specifically optimized for measuring phase differences. This localized optimization maintains manufacturing consistency through a unified process framework while achieving the measurement precision required for accurate auto-focusing.
4Reliability
If micro-lenses are customized for different pixel types, then sensitivity and signal-to-noise ratio improve, but manufacturing time and process steps increase
Solution Approach 1:
The patent applies parameter changes by adjusting micro-lens height and curvature parameters during the manufacturing process to match pixel type requirements. By controlling etch depth or material deposition parameters, the system creates micro-lenses with first heights for image sensing pixels and second heights for phase detection pixels within the existing manufacturing workflow. This approach improves signal-to-noise ratio and sensitivity through optimized light focusing while minimizing additional manufacturing time by integrating parameter variation into the standard process rather than adding separate manufacturing steps.
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 approach enables the image sensor to perform auto-focusing more accurately and enhance sensitivity by optimizing micro-lens curvatures for specific pixel types, improving both signal-to-noise and auto-focusing separation ratios.
Implementation Method 1
a first micro-lens disposed on each of the plurality of image sensing pixels to have a first height, and a second micro-lens disposed to vertically overlap the two phase detection subpixels
Data Source
AI summary
An image sensor is presented which includes a pixel array including a plurality of image sensing pixels in a substrate, a phase detection shared pixel in the substrate, the phase detection shared pixel including two phase detection subpixels arranged next to each other, a color filter fence disposed on the plurality of image sensing pixels, and the phase detection shared pixel, the color filter fence defining a plurality of color filter spaces, a plurality of color filter layers respectively disposed in the plurality of color filter spaces on the plurality of image sensing pixels, and the phase detection shared pixel, a first micro-lens disposed on each of the plurality of image sensing pixels to have a first height, and a second micro-lens disposed to vertically overlap the two phase detection subpixels of the phase detection shared pixel and to have a second height greater than the first height.