Metasurface Pillar Profiles for Mass-Produced Optical Variation
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Solution Overview
Problem
Existing metasurface structures face challenges in achieving mass production at low cost while maintaining distinct optical performance, particularly in designing non-rectangular pillar elements using conventional lithography methods.
Innovation Solution
A metasurface structure is formed with a substrate having distinct first and second regions, each containing pillar elements with different non-rectangular sectional profiles, surrounded by an encapsulation material, and utilizing a multi-step photolithography and etching process to create these elements, including the use of silicon oxide as a dielectric and encapsulation material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional lithography methods are used to form metasurface structures, then mass production at low cost is achieved, but the ability to create distinct non-rectangular pillar elements with varied optical properties is limited
Solution Approach 1:
The substrate is divided into multiple regions (first region, second region, third region) where each region receives different exposure conditions during photolithography. This segmentation allows different pillar element profiles (rectangular, trapezoidal, inverted trapezoidal, parallelogram) to be formed in different regions using the same lithography tool, enabling mass production with varied optical properties.
Solution Approach 2:
Different exposure conditions are applied to different regions of the substrate during photolithography. The first region receives a first exposure condition, the second region receives a second exposure condition, and the third region receives a third exposure condition. This local quality approach creates distinct pillar element profiles in different regions while using conventional mass production lithography equipment.
2Manufacturing precision
If electron beam lithography is used to create metasurfaces with distinct optical performance, then precise non-rectangular pillar elements are formed, but mass production at low cost becomes difficult
Solution Approach 1:
The invention uses conventional lithography steppers and scanners (copying technology) to replicate precise non-rectangular pillar element profiles across large substrate areas. By using photolithography with region-specific exposure conditions, the method copies the desired profiles mass-producibly without requiring expensive electron beam lithography for each individual element.
Solution Approach 2:
The invention changes exposure parameters (exposure conditions) during photolithography to control pillar element profile formation. By adjusting exposure conditions for different regions, precise non-rectangular profiles (trapezoidal, inverted trapezoidal, parallelogram) are achieved using conventional lithography equipment, enabling mass production with high precision.
3Device complexity
If uniform exposure conditions are applied during photolithography, then processing simplicity is maintained, but the ability to create varied pillar element profiles across different regions is lost
Solution Approach 1:
The photolithography process uses dynamic exposure conditions that can be adjusted for different regions. The exposure conditions are changed between regions during the same lithography run, allowing the process to adapt and create varied pillar element profiles (rectangular, trapezoidal, inverted trapezoidal, parallelogram) without requiring separate processing steps for each region.
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 method enables the cost-effective mass production of metasurface structures with varied optical properties by ensuring precise formation of non-rectangular pillar elements, enhancing optical performance and scalability.
Implementation Method 1
A photolithography process is performed on the first photoresist layer in the first region with a first exposure condition, and a photolithography process is performed on the first photoresist layer in the second region with a second exposure condition different from the first exposure condition
Implementation Method 2
Using the photoresist patterns with different profiles as an etching hard mask, the amorphous silicon layer is subjected to a first etching process, thereby forming pillar elements with different profiles
Data Source
AI summary
A metasurface structure includes a substrate having a first region and a second region not overlapping with the first region; a first pillar element within the first region on the substrate; and a second pillar element within the second region on the substrate. The first pillar element has a first sectional profile and the second pillar element has a second sectional profile that is different from the first sectional profile. At least one of the first sectional profile and the second sectional profile is of a non-rectangular shape.