Copper Electrode Lifting-Off Process for LCD Signal Delay
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Solution Overview
Problem
The existing methods for forming electrodes in LCDs using aluminum alloys face challenges with signal delay due to high resistivity, and the transition to copper (Cu) electrodes is hindered by adhesion issues, diffusion, and oxidation, requiring additional blocking and diffusion-preventing layers which increase manufacturing costs.
Innovation Solution
A method involving the deposition of a metal Cu thin film or composite thin film with a lifting-off process using a photoresist layer and a lifting-off solution, such as isopropanol with copper sulfate, to form low-resistance Cu electrodes and wires, eliminating the need for specialized etching solutions and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal Cu is used to form electrodes and wires, then resistivity decreases and electro-migration resistance increases, but adhesion to glass weakens and diffusion into semiconductor occurs
Solution Approach 1:
A blocking layer comprising Ti, Ta, Mg, Mo, Ag, In or Cr is introduced as an intermediary between the Cu electrodes and the glass substrate/semiconductor layers. This blocking layer serves dual functions: improving adhesion of Cu to glass and preventing Cu from diffusing into the semiconductor thin film, thereby resolving the harmful effects of using Cu while preserving its low resistivity and high electro-migration resistance.
2Reliability
If blocking layers are added to prevent Cu diffusion and improve adhesion, then reliability improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The blocking layer is designed to perform multiple functions simultaneously: it provides adhesion between Cu and glass, prevents Cu diffusion into semiconductor layers, and serves as part of the electrode structure. By consolidating these functions into a single layer rather than requiring separate adhesion layers and diffusion barriers, the patent reduces overall device complexity while maintaining reliability.
3Manufacturing precision
If conventional etching methods are used to form Cu patterns, then manufacturing precision is achieved, but specialized etching solutions are required increasing cost
Solution Approach 1:
The patent employs a photoresist lifting-off method instead of conventional etching with specialized solutions. The photoresist layer is deposited, patterned, and then lifted off using a simple aqueous solution (such as isopropanol with copper sulfate), leaving behind precisely patterned Cu electrodes. This approach replaces expensive, complex etching chemicals with a simple, disposable lifting-off solution that achieves the same patterning precision.
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 approach results in low-resistance metal Cu electrodes and wires that reduce signal delay and improve display quality, particularly beneficial for high-frequency LCDs, while simplifying the manufacturing process by eliminating the need for complex etching solutions and reducing production costs.
Implementation Method 1
removing the photoresist pattern and the metal Cu thin film or the composite thin film comprising the metal Cu thin film formed thereon from the resulting substrate
Implementation Method 2
forming a metal Cu thin film or a composite thin film comprising a metal Cu thin film
Data Source
AI summary
A method of forming a gate line and gate electrode and a method of manufacturing a TFT array substrate. The metal gate line and gate electrode can be formed by: providing a substrate, forming a photoresist layer on the substrate, a photoresist pattern being formed complementary with that of the gate line and gate electrode, forming a metal Cu thin film or a composite thin film comprising a metal Cu thin film on the substrate, and removing the photoresist pattern and the metal Cu thin film or composite thin film comprising the metal Cu thin film formed thereon from the substrate.