Wire Grid Polarizer Formation on Large LCD Substrates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing nano imprint lithography processes struggle to reliably form metallic wire grid polarizers on large substrates for liquid crystal displays due to mechanical accuracy issues, leading to variations in line widths and inter-line spaces, which decreases mass production yield and polarizing characteristics.
Innovation Solution
A method involving forming a reflective layer on a substrate, applying a UV-hardenable photosensitive film, creating recess patterns, filling these with an etch masking material, and etching using the insulating film as a mask to achieve precise wire grid polarizing patterns with uniform line widths and spacings on substrates larger than 300 mm by 300 mm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional nano imprint lithography is used to form wire grid polarizers on large substrates, then the polarizing characteristics can be achieved, but mechanical accuracy issues cause variations in line widths and inter-line spaces, decreasing manufacturing precision and mass production yield
Solution Approach 1:
The patent introduces a photosensitive film as an intermediary layer between the stamp and the reflective layer. This film acts as a compliant medium that absorbs mechanical inaccurities during the imprinting process, allowing the rigid stamp pattern to be transferred with high precision to the reflective layer without directly transmitting mechanical errors from large substrate handling
Solution Approach 2:
The patent replaces direct mechanical contact imprinting with a two-stage process: first forming recesses in the photosensitive film, then filling with etch masking material. This substitutes the mechanical transfer process with a combination of mechanical recess formation followed by material deposition, eliminating direct mechanical pattern transfer errors
2Productivity
If the substrate size is increased to 300 mm by 300 mm or larger for mass production, then productivity increases, but mechanical accuracy during imprinting deteriorates, leading to non-uniform wire grid patterns
Solution Approach 1:
The patent segments the pattern transfer process into distinct stages: recess formation in photosensitive film, then separate etch masking material filling. This segmentation allows each stage to be optimized independently - the recess formation handles the large substrate area while the material filling ensures precise pattern definition, resolving the contradiction between large area processing and precision
3Device complexity
If direct etching of the reflective layer is performed without a photosensitive film, then the process complexity is reduced, but the line width and spacing uniformity cannot be controlled at nano scale
Solution Approach 1:
The patent performs preliminary action by forming recesses in the photosensitive film before etching the reflective layer. These pre-formed recesses serve as precise guides for the subsequent etching process, ensuring that the wire grid pattern is transferred with accurate line widths and spacings. The preliminary recess formation establishes the geometric constraints that guide the final pattern formation
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
This method improves the uniformity and accuracy of wire grid polarizing patterns, enhancing the polarizing characteristics and enabling reliable mass production on large substrates, thereby maintaining high transmittance and polarizing efficiency.
Implementation Method 1
forming a UV-hardenable photosensitive film above the reflective layer; bonding an imprinting stamp having a predetermined engraved pattern with the photosensitive film and thereafter hardening the photosensitive film
Data Source
AI summary
A method of forming a wire grid polarizing pattern across the relatively large surface area of a display substrate includes using a nano imprint lithograph process wherein wire grid polarizing patterns are formed by bonding a stamp having a stamping area substantially smaller than that of the substrate with successive reticle areas of the substrate, where the substrate has a photosensitive film deposited thereon and where the stamping is such that recesses having a predetermined depth are formed in the photosensitive film, and then filling the recesses with an insulating film and etching it using the insulating film as a mask. Since mechanical misalignment margin is acceptable from one reticle area to the next, a wire grid polarizing pattern with a uniform line width and spacings in each reticle area can be formed on a substrate having a large area.