Meta-Optical Layer Stack for Low-Reflectance Etch Stop Design
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Solution Overview
Problem
Existing diffractive optical devices face challenges in reducing reflectance due to the limited materials available for etch stop layers, which are used to protect lower layers during etching, leading to restricted options for refractive index adjustments.
Innovation Solution
The meta-optical device incorporates a first functional layer with a combination of layers having different etch rates and refractive indices, including an etch stop layer and a layer with a refractive index that complements the etch stop layer to minimize reflectance at interfaces, and additional layers to enhance optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an etch stop layer is used to protect lower layers during etching, then manufacturing reliability is improved, but reflectance increases due to refractive index differences at interfaces
Solution Approach 1:
The patent applies composite materials by creating a multi-layer functional layer structure where each layer has different refractive indices. The first functional layer includes an etch stop layer with lower etch rate and a first layer with refractive index different from the etch stop layer, forming a composite structure that simultaneously provides etching protection and reduces reflectance through refractive index gradient matching.
Solution Approach 2:
The patent changes the refractive index parameter by selecting materials with specific refractive indices for different layers. The etch stop layer has a first refractive index, the first layer has a second refractive index different from the etch stop layer, and the second layer has a third refractive index, creating a gradient that reduces reflectance while maintaining etching selectivity.
2Manufacturing precision
If material selection for etch stop layer is limited by etch rate requirements, then etching selectivity is improved, but refractive index adjustment freedom decreases
Solution Approach 1:
The patent segments the functional layer into multiple sub-layers (etch stop layer, first layer, second layer) where each segment has optimized properties. The etch stop layer provides etching selectivity while the first and second layers provide refractive index control, allowing independent optimization of etching and optical properties without compromising either.
Solution Approach 2:
By using composite material structure with multiple layers having different refractive indices and etch rates, the patent achieves both etching selectivity (through the etch stop layer) and refractive index control (through the first and second layers), resolving the contradiction between manufacturing precision and adaptability.
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 configuration effectively reduces reflectance and maintains the desired optical performance by precisely controlling etch rates and refractive indices, ensuring accurate phase modulation and transmission.
Implementation Method 1
the first functional layer including a first-first layer with an etch rate, lower than an etch rate of the second peripheral material, and a first-second layer having a refractive index different from a refractive index of the first-first layer
Implementation Method 2
one of the refractive index of the first-first layer and the refractive index of the first-second layer may be greater than (n1*n2)1/2, and the other of the refractive index of the first-first layer and the refractive index of the first-second layer may be less than (n1*n2)1/2
Implementation Method 3
Diffractive optical devices using a meta-structure may obtain various optical effects that cannot be obtained by known refractive devices
Implementation Method 4
the nanostructure is designed such that a phase delay profile set for each position is satisfied to obtain desired optical performance
Data Source
AI summary
Provided is a meta-optical device including a substrate, a first meta-structure layer provided on the substrate, the first meta-structure layer including a first nanostructure having a sub-wavelength shape dimension and a first peripheral material provided adjacent to the first nanostructure, a second meta-structure layer provided on the first meta-structure layer, the second meta-structure layer including a second nanostructure having the sub-wavelength shape dimension and a second peripheral material provided adjacent to the second nanostructure, and a first functional layer provided between the first meta-structure layer and the second meta-structure layer, the first functional layer including a first-first layer having an etch rate that is lower than an etch rate of the second peripheral material, and a first-second layer having a refractive index that is different from a refractive index of the first-first layer.