Image Sensor Pixel Dielectric Element Crosstalk Reduction
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Solution Overview
Problem
Image sensors face challenges such as crosstalk, pixel size shrinkage limits, shadowing effects, and complex fabrication processes, which affect optical efficiency and manufacturing yield, particularly in small pixel designs.
Innovation Solution
The design replaces traditional micro lenses and color filter layers with a single dielectric element that combines light focusing and color filtering functions, using a complex refractive index material with a gap between elements to reduce optical stack thickness and improve manufacturing simplicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional micro lenses and color filter layers are used, then light focusing and color filtering functions are achieved, but optical stack thickness increases causing crosstalk
Solution Approach 1:
The patent combines the micro lens and color filter layer into a single integrated element. This merged structure performs both light focusing and color filtering functions simultaneously, reducing the overall optical stack thickness from separate layers to a unified component, thereby minimizing crosstalk between adjacent pixels.
Solution Approach 2:
The integrated element serves multiple functions: it acts as both a micro lens for light focusing and a color filter for wavelength selection. This multi-functional design eliminates the need for separate optical components, reducing thickness while maintaining both focusing and color filtering capabilities.
2Area of stationary object
If pixel size is reduced to increase resolution, then image sensor density improves, but crosstalk increases due to diffraction when wavelength is comparable to aperture size
Solution Approach 1:
By merging the micro lens and color filter into a single element, the patent achieves a more compact optical path that remains effective even in reduced pixel sizes. The integrated design maintains proper light focusing and color filtering without requiring separate layers that would increase the optical path length in small pixels.
Solution Approach 2:
The patent optimizes the parameters of the integrated element (such as curvature radius, thickness, and refractive index) to maintain effective light focusing and color filtering in sub-diffraction-limit pixel sizes. By carefully adjusting these parameters, the system achieves reduced crosstalk despite the small aperture size.
3Reliability
If multiple coating, lithography and etching steps are used for color filters and microlens array, then optical functionality is achieved, but fabrication complexity and cost increase
Solution Approach 1:
The patent merges the manufacturing processes for micro lenses and color filters into a single integrated fabrication sequence. Instead of separate coating, lithography, and etching steps for each component, the integrated element is fabricated in one unified process, significantly reducing fabrication complexity and improving yield.
Solution Approach 2:
The single integrated element requires a single fabrication process that simultaneously creates both the lens and color filter functions. This universal approach eliminates the need for multiple specialized manufacturing steps, reducing overall process complexity while maintaining full optical functionality.
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 reduces crosstalk, enhances light collection efficiency, and simplifies the fabrication process, enabling smaller pixel sizes while maintaining high optical performance and reducing manufacturing defects.
Implementation Method 1
The second element is an element for filtering color and focusing incident light into said first element
Implementation Method 2
The second element is an element for filtering color and focusing incident light into said first element
Data Source
AI summary
The present disclosure concerns an image sensor comprising a set of pixels, wherein each pixel of the set comprises a first and a second element, the first element comprising a photodiode module unit, and the second element being an element for filtering color and focusing incident light into said first element. The image sensor further comprises at least two consecutive pixels from the set of pixels, for which first elements are put side by side, and wherein the image sensor comprises a gap between second elements of said at least two consecutive pixels.