TFT Substrate Layered Electrodes and Aluminum Oxide Intermediary
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Solution Overview
Problem
The existing TFT substrates for liquid crystal displays face issues with film floating of insulating films on transparent conductive films, interface reaction between oxide semiconductor films and metal electrodes, and high interface resistance, which affect the performance and reliability of the TFTs, particularly in FFS systems requiring high transmittance and wide viewing angles.
Innovation Solution
A TFT substrate design with a gate electrode and auxiliary capacitance electrode on a substrate, featuring a semiconductor film electrically connected to both surfaces of the source and drain electrodes, and a layered structure of source and drain electrodes to reduce interface resistance and prevent film floating, using oxide semiconductors like InGaZnO for high mobility and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If oxide semiconductor film is used for high mobility, then device performance is improved, but interface reaction with metal electrodes occurs causing high interface resistance
Solution Approach 1:
An aluminum oxide insulating film is introduced as an intermediary layer between the oxide semiconductor film and the source/drain electrodes. This intermediary layer prevents direct contact and interface reaction between the oxide semiconductor and metal electrodes, thereby reducing interface resistance while maintaining the high mobility benefits of oxide semiconductors.
2Ease of manufacture
If insulating film is formed on transparent conductive film, then device structure is completed, but film floating occurs reducing reliability
Solution Approach 1:
The aluminum oxide insulating film is formed preliminarily on the transparent conductive film before forming the oxide semiconductor film. This preliminary anti-action prevents the film floating problem by providing a stable base layer that prevents subsequent films from detaching, thereby ensuring device reliability while maintaining ease of manufacture.
3Ease of manufacture
If oxide semiconductor film is etched selectively, then pattern formation is simplified, but dissolution in acid solution occurs
Solution Approach 1:
The aluminum oxide insulating film serves as a protective intermediary that prevents the oxide semiconductor film from direct exposure to acid solutions during etching processes. This allows selective etching and pattern formation to proceed while preventing unwanted dissolution of the oxide semiconductor material, maintaining both ease of manufacture and reliability.
Data Source
AI summary
A TFT substrate includes a TFT including a source electrode having a lower source electrode and an upper source electrode, which are electrically connected to each other, and a drain electrode having a lower drain electrode and an upper drain electrode, which are electrically connected to each other. The lower source electrode and the lower drain electrode are in contact with a lower surface of the semiconductor film, and the upper source electrode and the upper drain electrode are in contact with an upper surface of the semiconductor film.