Thin-Film Transistor Composite Electrode for Light Leakage Control
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Solution Overview
Problem
In liquid crystal displays (LCDs), light leakage occurs due to the poor adhesion of copper (Cu) processes, leading to an undercut structure in thin film transistor (TFT) panels, which reduces the contrast ratio, and existing barrier layers struggle to form protruding parts effectively.
Innovation Solution
A thin film transistor with composite electrodes comprising a barrier layer and an electrode layer, where the barrier layer has a protruding part extending 0.3 to 0.5 um, made from materials like Mo, Ti, or Nb with metal oxides such as TiO2, TaO2, or Nb2O5, and the electrode layer is copper, manufactured using specific etching processes to prevent undercut structures and improve adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If copper (Cu) process is used for electrode layer, then electrical conductivity is improved, but adhesion is worsened causing undercut structure
Solution Approach 1:
The patent uses a composite barrier layer structure combining Mo/Ti metal layer with metal oxide layer (TiO2, TaO2, or Nb2O5). This composite material approach provides both excellent adhesion to the substrate and good electrical conductivity, while preventing the undercut structure formation that occurs with pure copper processes.
2Object-affected harmful factors
If barrier layer protruding part is extended, then light leakage is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes the protruding part length of the barrier layer to a specific range (0.3-0.5 μm) and controls the metal oxide content (1-10% by mass). By precisely controlling these parameters, the invention achieves effective light leakage prevention while maintaining manufacturability through standard semiconductor fabrication processes.
3Reliability
If metal oxide content is increased in barrier layer, then adhesion is improved, but electrical conductivity is worsened
Solution Approach 1:
The patent precisely controls the metal oxide content to be within 1-10% by mass in the barrier layer. This optimized composition ensures sufficient adhesion to the substrate while maintaining adequate electrical conductivity for transistor operation, resolving the trade-off between adhesion and conductivity.
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 solution relieves light leakage and enhances the contrast ratio by allowing longer protruding barrier layers, improving adhesion and preventing undercut structures in TFT panels.
Implementation Method 1
Due to poor adhesion of Cu, it is generally accompanied by metal deposition of barrier layers
Implementation Method 2
a part of the polarized light to emit from an upper polarizer, which causes light leakage
Data Source
AI summary
A thin film transistor and a manufacturing method thereof are provided. The thin film transistor includes a composite electrode including a barrier layer and an electrode layer. The barrier layer has a protruding part relative to the electrode layer, an orthographic projection of the protruding part on the composite electrode protrudes beyond an orthographic projection of the electrode layer on the composite electrode, and a length of the protruding part ranges from 0.3 um to 0.5 um. The thin film transistor and the manufacturing method thereof of the present disclosure can relieve light leakage, thereby improving a contrast ratio of products.