Signal Wiring Taper Angle and Copper-Titanium Layering for Display Reflectance
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Solution Overview
Problem
High resolution display panels face issues with increased reflectance due to larger metal wiring areas, which deteriorate display quality, especially black image quality.
Innovation Solution
A display device with signal wiring featuring a copper main conductive layer and a titanium capping layer, along with an adhesion-improving layer, is designed with specific thicknesses and taper angles to reduce reflectance. The manufacturing method involves forming a multi-layered structure and using etching gases like SF6 and Cl2 to create a metal pattern with a low reflectance layer, including titanium, which overlaps the copper layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the metal wiring area is increased to achieve high resolution display, then the display resolution is improved, but the reflectance of external light increases
Solution Approach 1:
The patent applies composite materials by creating a multi-layered metal wiring structure consisting of a copper-containing layer and a titanium-containing layer. The copper layer provides high electrical conductivity while the titanium layer reduces external light reflectance. This composite structure resolves the contradiction by combining materials with complementary properties to achieve both high resolution and low reflectance.
Solution Approach 2:
The patent applies local quality by making the titanium-containing layer overlap only a portion of the upper surface of the copper-containing layer, specifically at regions where reflectance needs to be reduced. This partial overlapping approach locally modifies the surface properties to reduce reflectance while maintaining the overall wiring functionality and minimizing the impact on display resolution.
2Reliability
If the copper layer thickness is increased to improve electrical conductivity, then the electrical conductivity is improved, but the reflectance increases
Solution Approach 1:
The patent uses composite materials to resolve this contradiction by combining a copper-containing layer (for electrical conductivity) with a titanium-containing layer (for reduced reflectance). The copper layer can be made sufficiently thick to ensure good electrical conductivity, while the titanium layer on top reduces the overall reflectance of the wiring structure.
Solution Approach 2:
The titanium-containing layer is applied locally on the copper-containing layer to specifically address the reflectance issue without requiring a complete redesign of the copper layer structure. This allows the copper layer to maintain its optimal thickness for conductivity while the titanium layer locally reduces reflectance where it contacts the copper surface.
3Object-affected harmful factors
If the taper angle of the metal pattern is increased to reduce reflectance, then the reflectance is reduced, but the manufacturing precision becomes more difficult to control
Solution Approach 1:
The patent applies parameter changes by optimizing the taper angle of the metal pattern to be between 70° and 90°. This specific angular range was selected to balance reflectance reduction with manufacturability. The parameter optimization allows achieving low reflectance while maintaining reasonable manufacturing precision through controlled etching processes.
Solution Approach 2:
The multi-layered composite structure of copper and titanium layers works synergistically with the optimized taper angle to reduce reflectance. The composite material structure, combined with the specific angular geometry, achieves reflectance reduction through both material properties and geometric configuration, making the system more robust to manufacturing variations.
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 solution effectively reduces external light reflectance, improving display quality by optimizing the metal pattern's taper angle and adhesion, thereby enhancing the characteristics of the signal wiring.
Implementation Method 1
a low reflectance layer including titanium. Thus, reflectance of an external light by a metal pattern may be reduced
Implementation Method 2
The metal pattern may be dry-etched with an etching gas by applying the remaining photoresist pattern as a mask to remove the upper tip. The etching gas may include a fluorine-containing compound and a chlorine-containing compound.
Data Source
AI summary
A display device includes a thin film transistor on a base substrate and a signal wiring electrically connected to the thin film transistor. The signal wiring includes a main conductive layer including copper, and a capping layer including titanium the capping layer overlapping a portion of an upper surface of the main conductive layer. The signal wiring has a taper angle in a range of about 70° to about 90°. A thickness of the capping layer is in a range of about 100 Å to about 300 Å, and a thickness of the main conductive layer is in a range of about 1,000 Å to about 20,000 Å.