Wire Grid Polarizer Fabrication via Interference Lithography
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The high cost of polarizing films in liquid crystal displays (LCDs) and the challenge of fine patterning large-area wire grid polarizers for LCDs in manufacturing processes.
Innovation Solution
The use of interference lithography with a half Dyson optical system to pattern fine geometry lines and spaces on a large-area substrate, involving a method that includes depositing a bottom anti-reflective coating, a photoresist layer, and exposing it with a phase grating mask to create a grating pattern, which is then etched to form a wire grid polarizer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polarizing films are used to polarize LCD, then polarization function is achieved, but manufacturing cost increases significantly
Solution Approach 1:
The patent replaces expensive polarizing films with a cost-effective wire grid structure fabricated directly on the glass substrate. The wire grid is created through a multi-step process involving photoresist coating, interference lithography exposure, and aluminum deposition, resulting in a durable, integrated polarization solution that eliminates the need for separate polarizing film layers.
Solution Approach 2:
The patent combines the polarization function with the glass substrate by directly patterning the wire grid structure onto the substrate surface. This integration merges the structural support function of the glass with the polarization function, eliminating the need for separate polarizing film components and reducing overall manufacturing complexity.
2Ease of manufacture
If wire grid polarization is used instead of polarizing films, then manufacturing cost is reduced, but fine patterning of large-area substrates becomes challenging
Solution Approach 1:
The patent divides the large-area substrate patterning process into multiple manageable zones using a tiled exposure approach. The substrate is exposed in sequential regions, with each exposure creating a portion of the overall wire grid pattern. This segmentation allows standard lithography equipment to achieve high precision on large areas that would otherwise be beyond its capability.
Solution Approach 2:
The patent introduces temporal dimension to the patterning process by using sequential exposures across different regions of the substrate. Instead of attempting to pattern the entire large area simultaneously, the system moves through different spatial zones in time, achieving comprehensive coverage with maintained precision through systematic multi-step exposure and development cycles.
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 reduces the cost of manufacturing wire grid polarizers by enabling efficient patterning of large-area substrates, resulting in a cost-effective and high-quality wire grid polarizer for LCDs.
Implementation Method 1
exposing the photoresist layer with an image from a phase grating mask. The exposure with the phase grating mask is done by imaging the ±1 diffraction orders from the phase grating mask onto the substrate
Implementation Method 2
The beams from the opposing areas are combined at the substrate and interfere to create a grating pattern having twice the spatial frequency as the grating on the phase grating mask
Implementation Method 3
depositing a photoresist layer over the bottom anti-reflective coating layer, and exposing the photoresist layer with an image from a phase grating mask
Data Source
AI summary
The present disclosure generally relates to systems and methods for manufacturing wire grid polarizers for LCDs using interference lithography, which are also useful for generating large-area grating patterns. In one embodiment, a method includes depositing a bottom anti-reflective coating layer over an aluminum coated flat panel display substrate, depositing a photoresist layer over the bottom anti-reflective coating layer, and exposing the photoresist layer with an image from a phase grating mask. The exposure with the phase grating mask is done by imaging the ±1 diffraction orders from the phase grating mask onto the substrate using a half Dyson optical system. A plurality of half Dyson systems are generally used in parallel to pattern fine geometry lines and spaces of a wire grid polarizer for a large area substrate. Each half Dyson system includes a primary mirror, a positive lens and a reticle.