Wire Grid Polarizer Fabrication via Block Copolymer Alignment
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Solution Overview
Problem
Existing wire grid polarizers face challenges in achieving uniformity and optical quality due to irregularities in the conductive wire patterns, such as hillocks, which affect the polarization performance and extinction ratio, especially at smaller wavelengths.
Innovation Solution
A method involving sequential deposition of conductive wire patterns and guide patterns on a substrate, followed by hydrophobic treatment, neutral layer coating, and alignment of a block copolymer to selectively remove blocks and pattern the conductive wire layer, ensuring uniformity and preventing hillock formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional wire grid polarizer fabrication methods are used, then the manufacturing process is simple, but the uniformity of conductive wire patterns deteriorates due to hillock formation
Solution Approach 1:
The fabrication process is divided into multiple sequential steps: depositing conductive wire patterns, forming guide patterns, hydrophobic treatment, neutral layer coating, block copolymer alignment, selective removal, and final patterning. This segmentation allows each step to be optimized independently, achieving uniform wire patterns without hillocks while maintaining manageable process complexity through systematic breakdown.
Solution Approach 2:
Guide patterns are formed in advance to define the precise locations where conductive wires should be deposited. The hydrophobic treatment and neutral layer are applied preliminarily to prepare the surface for uniform block copolymer alignment. These preliminary actions ensure that the final wire patterns are uniform and free from hillocks before the actual patterning occurs.
2Length of moving object
If the period of wire grid polarizer is reduced for smaller wavelengths, then the polarization performance improves, but the uniformity and optical quality deteriorate due to hillocks
Solution Approach 1:
The method applies local quality control through guide patterns that precisely define where conductive wires should form, and through hydrophobic treatment that creates localized surface properties. This ensures uniform wire patterns even at small periods required for smaller wavelengths, preventing hillock formation while maintaining the reduced period for improved polarization performance.
Solution Approach 2:
Block copolymer serves as an intermediary material that enables precise patterning at small scales. The neutral layer acts as an intermediary between the hydrophobic surface and the block copolymer, ensuring uniform alignment. This intermediary approach allows achieving uniform wire patterns at reduced periods without hillock formation, enabling better polarization performance at smaller wavelengths.
3Reliability
If conventional patterning methods are used, then the fabrication process is simple, but the polarization-to-extinction ratio deteriorates due to irregularities in wire patterns
Solution Approach 1:
The patterning process is segmented into multiple controlled steps: guide pattern formation, hydrophobic treatment, neutral layer coating, block copolymer alignment, selective removal, and final wire pattern formation. This segmentation ensures uniform wire patterns with consistent spacing and dimensions, eliminating irregularities that would degrade polarization performance while keeping each individual step manageable.
Solution Approach 2:
The method changes physical and chemical parameters at each step: surface energy through hydrophobic treatment, layer thickness through controlled coating, and material properties through block copolymer selection. These parameter changes enable precise control over wire pattern uniformity, achieving high polarization-to-extinction ratios without excessive overall process complexity.
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 results in a wire grid polarizer with excellent optical properties and improved polarization performance, particularly at smaller wavelengths, by maintaining a uniform period and reducing irregularities, thus enhancing the polarization-to-extinction ratio.
Implementation Method 1
aligning the block copolymer filled in the trenches, selectively removing blocks of one monomer among the two monomer from the aligned block copolymer such that the other monomer among the two monomers remains in the trenches
Implementation Method 2
hydrophobically treating surfaces of the conductive wire pattern layer exposed in the trenches, and the guide patterns
Data Source
AI summary
A method of fabricating a wire grid polarizer includes sequentially depositing a conductive wire pattern layer, and a plurality of guide patterns which forms one or more trenches therebetween on the conductive wire pattern layer, hydrophobically treating surfaces of the conductive wire pattern layer exposed in the trenches, and the guide patterns, coating the hydrophobically treated conductive wire pattern layer in the trenches with a neutral layer to partially fill the trenches, filling a remainder of the trenches with a block copolymer of two monomers with different etching rates, aligning the block copolymer filled in the trenches, selectively removing blocks of one monomer among the two monomers from the aligned block copolymer, and patterning the conductive wire pattern layer by using blocks of the other monomer among the two monomers remaining in the trenches and the guide patterns as a mask.