Metasurface Image Sensor Routing for Uniform Color Sensitivity
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Solution Overview
Problem
Existing image capture devices face challenges in achieving uniform quantum efficiency (QE) and sensitivity across different color pixels, leading to issues in white-balancing and requiring adjustments in photodiode sizes or binning to compensate for color differences.
Innovation Solution
Incorporating a metasurface routing layer over a color filter layer in image sensors, where metasurface regions are configured to route light of different colors to pixels, providing varying effective resolutions and angular sensitivity, thereby adjusting relative sensitivities without altering photodiode sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different sized photodiodes are used to compensate for color differences in quantum efficiency, then uniform sensitivity across colors is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies local quality by placing color-specific optical compensating structures (such as microlenses or optical compensating films) over individual color regions rather than using different photodiode sizes. Each color region receives tailored optical compensation to achieve uniform quantum efficiency while maintaining a uniform photodiode array, thus resolving the contradiction between sensitivity uniformity and device complexity
Solution Approach 2:
The patent introduces an intermediary optical compensating structure between the color filter layer and the microlens layer (or between the color filter and the photodiode) to mediate the light transmission differences for different colors. This intermediary layer equalizes the optical path and transmission characteristics for different wavelengths, achieving uniform quantum efficiency without modifying photodiode dimensions
2Reliability
If photodiode sizes are adjusted to equalize quantum efficiency across colors, then white-balancing performance is improved, but manufacturing precision requirements increase
Solution Approach 1:
Instead of manufacturing photodiodes with different sizes for different colors (which would require high precision), the patent applies local quality by placing color-specific optical compensating elements over each color region. This approach maintains uniform photodiode dimensions while achieving color-balanced sensitivity through optical path equalization, thereby reducing manufacturing precision requirements
Solution Approach 2:
The patent replaces the mechanical approach of varying photodiode physical dimensions with an optical approach using compensating structures (microlenses or optical films) to achieve the same white-balancing effect. This substitution eliminates the need for precise control of photodiode size variations and simplifies the manufacturing process
3Reliability
If binning is used to compensate for color differences, then sensitivity uniformity is improved, but resolution decreases
Solution Approach 1:
The patent introduces an optical compensating structure as an intermediary between the color filter layer and the photodiode array to equalize light transmission for different colors. This allows each pixel to maintain its full sensitivity and resolution capability while achieving uniform quantum efficiency across colors, avoiding the need for binning operations that would reduce resolution
4Reliability
If a metasurface routing layer is added to equalize quantum efficiency, then sensitivity uniformity and white-balancing are improved, but device complexity increases
Solution Approach 1:
The patent implements a metasurface routing layer that performs multiple functions simultaneously: it acts as an optical compensating structure to equalize quantum efficiency across different colors, serves as a routing layer to direct light to appropriate photodiodes, and maintains a planar compact structure. This multi-functionality reduces the need for separate compensating layers, thereby mitigating the increase in device complexity
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 metasurface routing layer enhances pixel sensitivity and reduces noise in white-balancing procedures by equalizing QE across colors, maintaining resolution and modulation transfer function (MTF), and improving autofocus performance.
Implementation Method 1
The metasurface layer includes a first metasurface region configured to pass light of the first color to the first color region and thereby define a first effective resolution for the first pixel
Data Source
AI summary
Systems, apparatuses, and methods for an image sensor using a metasurface routing layer are described. An image capture device includes an array of pixels, a color filter layer disposes over the array of pixels, and a metasurface layer disposed over the color filter layer. The color filter layer includes a first color region over the first pixel for a first color and a second color region over the second pixel for a second color. The metasurface layer includes a first metasurface region to pass light of the first color to the first color region, defining a first effective resolution for the first pixel and a second metasurface region to pass light of the second color to the second color region, defining a second effective resolution for the second pixel larger than the first effective resolution. The second metasurface region at least partially overlaps the first metasurface region.