Meta-Layer Image Sensor Coating for Low-Reflectivity Nano-Structures
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Solution Overview
Problem
The challenge in CMOS image sensors is to reduce the reflectivity of nano-structures while maintaining optical effectiveness, which is affected by the focal length and arrangement of elements.
Innovation Solution
An image sensor design incorporating a meta layer with nano-structures coated by an anti-reflective layer, where the anti-reflective layer is non-conformally applied to enhance optical performance by reducing reflectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an anti-reflective layer is conformally coated on nano-structures, then the manufacturing process is simple, but the reflectivity is not sufficiently reduced and optical effectiveness deteriorates
Solution Approach 1:
The patent applies non-conformal coating where the anti-reflective layer is deposited to different thicknesses on different parts of the nano-structures. The coating thickness varies locally - thicker on top surfaces and thinner or absent on sidewalls - creating locally optimized optical properties that reduce reflectivity while maintaining manufacturing feasibility through controlled deposition parameters
2Object-affected harmful factors
If the anti-reflective layer is non-conformally coated, then reflectivity is reduced and optical effectiveness is enhanced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent achieves non-conformal coating by changing deposition parameters including deposition angle, substrate rotation speed, and coating material properties. These parameter variations during the coating process naturally create the desired non-uniform thickness distribution without requiring complex post-processing or high-precision manual control, thus reducing manufacturing precision requirements while achieving the optical performance goals
3Object-affected harmful factors
If nano-structures are used for anti-reflection, then optical performance is improved, but the device complexity increases due to additional layers and structures
Solution Approach 1:
The patent integrates multiple functions into the anti-reflective coating layer itself. The same layer provides both the anti-reflective function through its non-uniform thickness profile and the optical phase control function through its refractive index and thickness distribution. This multi-functionality reduces device complexity by eliminating the need for separate anti-reflective and phase control layers, achieving both goals with a single integrated structure
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 design effectively reduces reflectivity and enhances optical effects by tuning the phase difference through the use of nano-structures and an anti-reflective layer with specific aspect ratios and refractive index relationships.
Implementation Method 1
an anti-reflective layer coated on the meta layer. The anti-reflective layer includes a first portion on a top surface of a first nano-structure of the top nano-structures and a second portion on a sidewall of the first nano-structure
Implementation Method 2
a refractive index of the anti-reflective layer is greater than a refractive index of the protective layer, and the refractive index of the protective layer is greater than 1
Data Source
AI summary
The image sensor includes a photoelectric conversion layer, a color filter layer disposed on the photoelectric conversion layer, a buffer layer disposed on the color filter layer, a meta layer, and an anti-reflective layer coated on the meta layer. The meta layer includes a lining layer on the buffer layer and a plurality of top nano-structures protruded from the lining layer in a direction away from the photoelectric conversion layer. The anti-reflective layer includes a first portion on a top surface of a first nano-structure of the top nano-structures and a second portion on a sidewall of the first nano-structure, and a height of the first portion is greater than a width of the second portion.