IGZO Array Substrate Cover Layer for Etching Protection
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Solution Overview
Problem
In the production of thin film transistor liquid crystal displays (TFT-LCD), the etching solution used in back-channel etching often damages the indium gallium zinc oxide (IGZO) active layer, affecting the characteristics of the TFTs.
Innovation Solution
An array substrate is designed with a cover layer comprising a metal conductive portion and a transparent insulating metal oxide portion, both made from the same metal element, which are electrically connected to the active layer, and formed using a process that eliminates the need for etching by converting a metal layer into a transparent insulating metal oxide through oxygen plasma bombardment, thereby protecting the active layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If back-channel etching is performed to manufacture TFT substrates, then the manufacturing process can be completed, but the etching solution damages the IGZO active layer
Solution Approach 1:
A cover layer is introduced as an intermediary protective structure between the etching environment and the active layer. This cover layer includes a metal conductive portion and a transparent insulating metal oxide portion, where the metal oxide portion acts as a barrier that prevents etching solution from reaching and damaging the active layer, while the metal conductive portion maintains electrical connectivity.
Solution Approach 2:
The cover layer is segmented into functionally distinct portions: a metal conductive portion for electrical conduction and a transparent insulating metal oxide portion for protection. This segmentation allows each portion to perform its specific function optimally - the metal portion conducts electricity while the metal oxide portion provides etching resistance and optical transparency.
2Reliability
If a cover layer with metal conductive portion and transparent insulating metal oxide portion is formed, then the active layer is protected from etching damage, but the device structure becomes more complex
Solution Approach 1:
Multiple functions are merged into a single cover layer structure. The cover layer simultaneously provides electrical conduction (through the metal conductive portion), optical transparency (through the transparent insulating metal oxide portion), and protection from etching (through the metal oxide barrier). This merging reduces the need for separate protective layers and simplifies the overall device architecture.
Solution Approach 2:
The cover layer is designed as a multi-functional component that performs multiple roles: it serves as a protective barrier against etching solutions, maintains electrical conductivity where needed, provides optical transparency for display applications, and can function as part of the TFT electrode structure. This multi-functionality reduces the total number of required layers and components.
3Manufacturing precision
If oxygen plasma bombardment is used to convert metal layer to transparent insulating metal oxide, then the manufacturing precision is improved, but the processing time increases
Solution Approach 1:
The conversion process utilizes changes in plasma parameters (oxygen content, power, pressure, temperature) to control the oxidation of the metal layer. By optimizing these parameters, the conversion to transparent insulating metal oxide can be achieved with high precision while minimizing processing time. The metal layer transforms into metal oxide through controlled plasma treatment that adjusts oxidation程度 to achieve the desired insulating and transparent properties.
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 prevents damage to the active layer during the wet etching process, significantly optimizing the characteristics of the TFTs and improving product yield.
Implementation Method 1
processing the array substrate to allow a region, which is not covered by the shielding layer, of the metal layer to be converted into a transparent insulating metal oxide
Implementation Method 2
converted into a transparent insulating metal oxide
Data Source
AI summary
An array substrate, a display device, a thin film transistor, and a method for manufacturing an array substrate are disclosed. The array substrate includes a base substrate, an active layer, and a cover layer. The active layer is on the base substrate, the cover layer is on a side, away from the base substrate, of the active layer and covers the array substrate, the cover layer includes a metal conductive portion and a transparent insulating metal oxide portion, the metal conductive portion and the transparent insulating metal oxide portion include an identical metal element, and the metal conductive portion is electrically connected to the active layer.