Image Sensor Anti-Reflection Structure for Higher Light Utilization
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Solution Overview
Problem
Image sensors face low light utilization efficiency due to color filters absorbing unwanted light and reflectivity issues from multiple layers with different refractive indices, leading to significant light loss and reduced performance.
Innovation Solution
An image sensor design incorporating a sensor substrate with anti-reflection elements featuring low-refractive index patterns and a high-refractive index layer, along with a color separating lens array and color filter array, to enhance light transmission and reduce reflectivity, optimizing the arrangement of low-refractive index patterns and fill factors based on incident light angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a color filter is used to sense light color, then light color detection is enabled, but light utilization efficiency deteriorates due to absorption of unwanted light
Solution Approach 1:
The patent removes the traditional color filter layer from the image sensor structure. Instead of using a color filter to detect light color, the invention uses a color separation lens array that optically separates different wavelengths of light before they reach the pixel array, thereby eliminating light absorption losses while maintaining color detection capability
Solution Approach 2:
The patent replaces the mechanical/optical filtering mechanism (color filter) with an optical lens-based separation mechanism (color separation lens array). The color separation lens array uses refraction and focal length differences to separate wavelengths, substituting the absorption-based color filter approach with a lens-based optical separation approach
2Adaptability or versatility
If multiple layers with different refractive indices are used in the image sensor, then functional requirements are met, but reflectivity increases causing light loss
Solution Approach 1:
The patent introduces an anti-reflection element as an intermediary layer between the color separation lens array and the pixel array. This element includes a low-refractive-index pattern layer and a high-refractive-index layer that act as optical intermediaries to reduce reflectivity at interfaces between layers with different refractive indices, thereby reducing light loss
Solution Approach 2:
The anti-reflection element uses a composite structure combining materials with different refractive indices (low-refractive-index pattern layer and high-refractive-index layer) to create an optimized optical interface. This composite material approach allows gradual refractive index transition, reducing reflection at layer boundaries
3Loss of energy
If the arrangement period and fill factor of low-refractive index patterns are increased for oblique incident light, then light transmission is improved, but device complexity increases
Solution Approach 1:
The patent applies different arrangement periods and fill factors of low-refractive-index patterns to different regions of the anti-reflection element based on the incident light angle. Regions receiving oblique light have optimized parameters different from regions receiving perpendicular light, creating locally optimized structures that improve light transmission without requiring complex variable parameters across the entire device
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 solution improves quantum efficiency and reduces reflectivity, resulting in enhanced light utilization and image quality while maintaining low manufacturing costs.
Implementation Method 1
an image sensor includes multiple layers having different refractive indices from one another, and incident light may be reflected by an interfacial layer
Implementation Method 2
an anti-reflection element provided on the sensor substrate, wherein the anti-reflection element includes a plurality of low-refractive index patterns and a high-refractive index layer provided between the plurality of low-refractive index patterns and the sensor substrate
Implementation Method 3
a color separating lens array configured to condense the light of the first wavelength on the plurality of first pixels after changing a phase of the light of the first wavelength and configured to condense the light of the second wavelength on the plurality of second pixels after changing a phase of the light of the second wavelength
Implementation Method 4
condense the light of the first wavelength on the plurality of first pixels after changing a phase of the light of the first wavelength
Implementation Method 5
a color filter array provided between the anti-reflection element and the color separating lens array, wherein the color filter array may include: a plurality of first color filters arranged to respectively correspond to the plurality of first pixels and configured to selectively transmit the light of the first wavelength
Implementation Method 6
a color filter may have low light utilization efficiency because the color filter absorbs light of colors other than the intended color of light
Implementation Method 7
a sensor substrate including a plurality of first pixels sensing light of a first wavelength and a plurality of second pixels sensing light of a second wavelength
Data Source
AI summary
An image sensor includes: a sensor substrate including a plurality of first pixels configured to sense light of a first wavelength and a plurality of second pixels configured to sense light of a second wavelength; and an anti-reflection element provided on the sensor substrate, wherein the anti-reflection element includes a plurality of low-refractive index patterns and a high-refractive index layer provided between the plurality of low-refractive index patterns and the sensor substrate.