Air-Gap Encapsulation for Nanostructured Optical Devices
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Solution Overview
Problem
Existing optical devices with nano-structured components require effective encapsulation materials that maintain a high refractive index contrast and mechanical protection, while incorporating air gaps to enhance optical performance.
Innovation Solution
The formation of optical devices with a support layer and encapsulation layer that includes openings filled with air, creating a high refractive index contrast between the optical device structures, support layer, and air gaps, using methods such as chemical vapor deposition and etching processes to achieve controllable air-gapped encapsulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If encapsulation material is used to provide mechanical protection, then mechanical protection is improved, but refractive index contrast deteriorates
Solution Approach 1:
The encapsulation structure is segmented into multiple distinct layers: a support layer providing mechanical protection and an encapsulation layer providing chemical protection. This segmentation allows each layer to be optimized for its specific function without compromising the other, resolving the contradiction between mechanical protection and optical performance.
Solution Approach 2:
Different regions of the encapsulation structure have different material compositions and properties. The support layer uses materials optimized for mechanical strength, while the encapsulation layer uses materials with refractive indices matched to the core structures. This local differentiation allows simultaneous achievement of mechanical protection and high refractive index contrast.
2Strength
If encapsulation material is used to provide mechanical protection, then mechanical protection is improved, but optical performance deteriorates
Solution Approach 1:
The encapsulation is divided into functional segments where the support layer handles mechanical protection and the encapsulation layer handles optical performance. This functional segmentation eliminates the trade-off by assigning different optimization goals to different layers.
Solution Approach 2:
The encapsulation structure uses composite material architecture with the support layer and encapsulation layer made from different material systems. The support layer may use silicon dioxide or silicon nitride for mechanical strength, while the encapsulation layer uses materials with refractive indices specifically selected to match the core, creating a composite structure that achieves both mechanical protection and optical performance.
3Reliability
If air gaps are introduced to improve refractive index contrast, then refractive index contrast is improved, but mechanical protection deteriorates
Solution Approach 1:
The air gaps are segmented and localized to specific regions between core structures where they provide optical benefit, while the support layer and encapsulation layer are positioned to provide continuous mechanical protection. This spatial segmentation allows air gaps to improve refractive index contrast without compromising overall mechanical integrity.
Solution Approach 2:
The support layer and encapsulation layer act as intermediary elements that mediate between the air gaps and the external environment. These intermediary layers provide the mechanical protection that would otherwise be lost due to the presence of air gaps, allowing the air gaps to fulfill their optical function without sacrificing mechanical strength.
4Reliability
If material thickness is reduced to improve optical performance, then optical performance is improved, but mechanical protection deteriorates
Solution Approach 1:
The encapsulation thickness is segmented and differentiated: the support layer can be thicker to provide mechanical protection, while the encapsulation layer can be thinner to minimize optical interference. This segmented thickness approach allows reduced overall material thickness for improved optical performance while maintaining adequate mechanical protection through the support layer.
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
Enhances optical performance by increasing refractive index contrast, allowing for reduced material thickness and improved mechanical protection of nano-structured optical devices.
Implementation Method 1
The etch process includes an etch chemistry that etches the sacrificial material at a higher rate than the encapsulation layer
Implementation Method 2
a high contrast between the refractive index of the material of the structures and the refractive index of the material between the structures is desirable to improve the optical device performance
Data Source
AI summary
Embodiments described herein relate to encapsulated optical devices and methods of forming optical devices with controllable air-gapped encapsulation. In one embodiment, a plurality of openings are formed in a support layer surrounding the plurality of optical device structures to create a high refractive index contrast between the optical device structures, the support layer, and the openings. In another embodiment, sacrificial material is disposed in-between the optical device structures and then an encapsulation layer is disposed on the optical device structures. The sacrificial material is removed, forming a space bounded by the encapsulation layer, the substrate, and each of the optical device structures. In yet another embodiment, the encapsulation layer is disposed over the optical device structures forming a space bounded by the encapsulation layer, the substrate, and each of the optical device structures.