Wire Grid Polarizer Protective Cap Corrosion Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wire grid polarizers used in systems for visible or ultraviolet light polarization are prone to corrosion, which degrades system performance and requires protection of the wires to maintain high contrast and transmission efficiency.
Innovation Solution
The implementation of a cap structure on the reflective ribs of the wire grid polarizer, which includes specific dimensions and materials to protect the ribs from corrosion and enhance performance by increasing the transmission of the predominantly-transmitted polarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire grid polarizer wires are made small and delicate with nanometer-sized pitch to achieve high performance, then polarization effectiveness is improved, but susceptibility to corrosion increases
Solution Approach 1:
A protective cap structure is introduced as an intermediary element between the wire grid polarizer wires and the corrosive environment. The cap covers the wire ends and sidewalls, preventing direct contact with moisture and oxygen while allowing the wire's optical function to remain intact. This mediator approach resolves the contradiction by shielding the vulnerable nanometer-scale wires from corrosion without altering their polarization effectiveness.
Solution Approach 2:
The protective cap is implemented as a thin film or shell structure that conforms to the wire geometry. This thin protective layer provides corrosion protection while minimizing impact on the wire's optical properties. The cap's thin-film nature allows it to protect the delicate nanometer-sized wires without significantly increasing device complexity or compromising the polarization function.
2Use of energy by moving object
If wire dimensions are reduced to nanometer scale for high performance, then transmission efficiency is improved, but structural stability deteriorates
Solution Approach 1:
The protective cap is applied beforehand to shield the nanometer-scale wires from environmental damage before corrosion can occur. This preventive approach cushions the structurally vulnerable wires against moisture and oxygen exposure, maintaining their structural integrity over time while preserving their high transmission efficiency.
Solution Approach 2:
The wire grid polarizer structure becomes a composite system combining the metal wires with a protective cap material (such as silicon dioxide or silicon nitride). This composite structure provides both the optical functionality of the metal wire and the protective properties of the cap material, resolving the contradiction between nanometer-scale transmission efficiency and structural stability.
3Reliability
If protective measures are added to prevent corrosion, then reliability is improved, but device complexity increases
Solution Approach 1:
The protective cap formation process is merged with the existing wire fabrication process, utilizing the same etch and deposition steps already present in the manufacturing flow. By combining the protective cap formation with existing process steps rather than adding separate operations, the solution improves corrosion resistance while minimizing the increase in device complexity.
Solution Approach 2:
The protective cap serves multiple functions simultaneously: it prevents corrosion, defines wire dimensions during etching, and provides a release layer for subsequent processing. This multi-functionality reduces the need for additional separate protective structures, thereby improving reliability without proportionally increasing device complexity.
Data Source
AI summary
Each wire 12 of a wire grid polarizer can include a cap 22 on a reflective rib 21. The cap 22, with dimensions and material as specified herein, can protect the reflective rib 21 from corrosion and can improve performance of the wire grid polarizer. The cap 22 can be located on the distal end 21d and the pair of sidewalls 21S of the reflective rib 21. Cap 22 chemistry can include CO, C═O, COO, aluminum fluoride, and aluminum oxide. Each cap 22 can have a maximum thickness ThCS on the sidewall 21S of the reflective rib 21 in an upper 50% (above plane 31) of the wire 12 farthest from the substrate 11. Each cap 22 can have a maximum thickness ThCS on the sidewall 21S that is greater than a maximum thickness ThCD of the cap 22 on the distal end 21d.