High Aspect Ratio Nano-pillar Fabrication via Composite Support
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fabricating nano-pillars with a substantially large aspect ratio for metasurface devices is challenging due to structural instability, as taller nano-pillars without increased width are prone to bending or toppling, complicating the achievement of complex optical functions.
Innovation Solution
A method involving coating and etching multiple materials to form high aspect ratio nano-pillars, where the height-to-width ratio is maintained by constructing the nano-pillars in two parts with a protective material filling to support the structure, preventing bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the nano-pillars are made taller to reduce diffraction dispersion and achieve more complex optical functions, then the optical performance is improved, but the aspect ratio becomes substantially large making fabrication difficult and the structure unstable
Solution Approach 1:
The patent divides the nano-pillar fabrication into multiple sequential steps: first forming a template structure with first material, then depositing second material, followed by selective etching to create the high aspect ratio nano-pillar structure. This segmentation of the fabrication process enables precise control over the nano-pillar dimensions and achieves the target aspect ratio that would be difficult to obtain through conventional single-step methods.
2Object-affected harmful factors
If the nano-pillars are made taller to reduce diffraction dispersion, then the diffraction dispersion is reduced, but the nano-pillars are likely to bend down or topple over
Solution Approach 1:
The patent employs a composite material structure consisting of first material forming the nano-pillar core and second material serving as a supporting matrix. This composite configuration provides mechanical reinforcement to the high aspect ratio nano-pillars, preventing bending and toppling while maintaining the tall structure necessary to reduce diffraction dispersion effects.
Solution Approach 2:
The second material acts as an intermediary supporting structure that provides mechanical stability to the first material nano-pillars. This intermediary layer enables the formation of tall, thin nano-pillars by distributing mechanical stresses and preventing structural failure, thus allowing the nano-pillars to achieve the height needed to reduce diffraction dispersion without compromising stability.
Data Source
AI summary
An optical device fabrication method includes: coating a first material over a surface of a substrate; etching a portion of the first material to obtain a target position for a nano-pillar; coating a second material over a portion of the surface of the substrate exposed through etching the portion of the first material, a height of the second material being equal to a height of the first material; coating a nano-material over a surface of the second material and the first material; etching the nano-material to remove a first portion of the nano-material and retain a second portion of the nano-material at the target position to form a part of the nano-pillar, a ratio of a height of the nano-pillar to a width of the nano-pillar ≥10; and filling a protective material in a space previously occupied by the first portion of the nano-material to support the nano-pillar.