TFT Array Diffusion Prevention Film for OLED Anode Stability
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Solution Overview
Problem
Existing TFT array units for OLED displays face challenges in achieving both satisfactory electric contact characteristics and preventing counter diffusion, particularly between aluminum-based anode electrodes and copper-based relay electrodes, which can lead to electro-migration and disconnection.
Innovation Solution
A diffusion prevention film made of aluminum-based oxide is formed on the boundary face of the electrodes, with a thickness between 1 to 6 nanometers, ensuring effective electrical connection and preventing counter diffusion by matching the material composition of the anode electrode, thereby maintaining low contact resistance and preventing electro-migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum-based anode electrode and copper-based relay electrode are directly connected, then electrical connection is established, but counter diffusion occurs leading to electro-migration and disconnection
Solution Approach 1:
An aluminum oxide diffusion prevention film is introduced as an intermediary layer between the aluminum-based anode electrode and copper-based relay electrode. This film acts as a mediator that prevents direct contact between the two metals, thereby blocking counter diffusion and electro-migration while still allowing electrical connection to be maintained through the insulating film with controlled resistance.
2Object-generated harmful factors
If diffusion prevention film is added between electrodes, then counter diffusion is prevented, but contact resistance increases
Solution Approach 1:
The thickness of the aluminum oxide diffusion prevention film is precisely controlled within the range of 1 to 6 nanometers. By optimizing this parameter, the film provides sufficient barrier properties to prevent counter diffusion while maintaining low enough resistance to ensure good electrical contact. The specific thickness range balances the competing requirements of diffusion prevention and electrical conductivity.
3Reliability
If high temperature crystallization process is used, then semiconductor film quality is improved, but manufacturing cost increases due to expensive substrate requirements
Solution Approach 1:
The crystallization temperature parameter is changed from high temperature (1000°C or more) to low temperature (600°C or less) processing. This parameter change enables the use of inexpensive glass substrates instead of expensive quartz substrates, significantly reducing manufacturing costs while still achieving sufficient crystallization of the semiconductor film for functional performance.
Solution Approach 2:
The conventional thermal field-based high temperature crystallization process is replaced with alternative methods such as laser annealing or plasma treatment that can achieve crystallization at lower temperatures. This substitution of the physical mechanism allows glass substrates to be used instead of quartz, reducing material costs while maintaining semiconductor film quality.
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 achieves non-defective contact characteristics with minimal counter diffusion, ensuring reliable electrical performance and preventing disconnection due to thermal history during manufacturing, thus enhancing the stability and reliability of the TFT array units.
Implementation Method 1
a diffusion prevention film made of an oxide having a main component same as the material constituting the electrode of the luminescence unit is formed on the boundary face of the electrode of the luminescence unit and the current supplying electrode
Implementation Method 2
a current supplying electrode connected electrically to an electrode of the luminescence unit and for connecting the electrode of the luminescence unit to the thin film transistor array via a contact hole of the interlayer insulation film
Data Source
AI summary
EL display has a luminescence unit having a luminescence layer being disposed between a pair of electrodes and a thin film transistor array unit controlling luminescence of the luminescence unit. An interlayer insulation film is disposed between the luminescence unit and the transistor array unit. An anode of the luminescence unit is connected electrically to the thin film transistor array via a contact hole of the interlayer insulation film. The thin film transistor array further has a current supplying relaying electrode that is connected to the anode of the luminescence unit via the contact hole of the interlayer insulation film. A diffusion prevention film is formed on the boundary face of the anode of the luminescence unit and the relaying electrode.