Oxide Layer Gate Electrode for LCD Array Substrate
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Solution Overview
Problem
The production of coplanar type thin film transistors (TFTs) for liquid crystal display devices is hindered by the need for multiple mask processes, increasing production costs and reducing productivity due to the requirement of a second insulating layer to protect the ZnO-based active layer.
Innovation Solution
A method involving the formation of a semiconductor layer, a gate electrode, and source and drain electrodes, with an oxide layer covering the gate electrode and corresponding to the semiconductor layer, reducing the need for the second insulating layer and simplifying the manufacturing process by using a halftone mask to pattern the metal layers and oxidizing the exposed metal pattern to form the oxide layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a second insulating layer is formed to protect the ZnO-based active layer from exposure, then the active layer is protected, but the number of mask processes increases
Solution Approach 1:
The patent removes the second insulating layer from the structure entirely. Instead of adding protective layers, the invention uses the gate electrode itself as the protective element by positioning it to cover the active layer, thereby eliminating the need for the second insulating layer and its associated mask process while still providing protection to the ZnO-based active layer
Solution Approach 2:
The gate electrode serves dual functions: it provides the electrical gating function necessary for TFT operation and simultaneously acts as a protective barrier over the active layer. This multi-functionality eliminates the need for separate protective insulating layers, reducing the number of mask processes required
2Reliability
If a second insulating layer is formed to prevent active layer exposure, then the active layer is protected, but production cost increases
Solution Approach 1:
The patent eliminates the second insulating layer and its associated mask process, directly reducing manufacturing steps and costs. The gate electrode structure is designed to provide both electrical function and protective function, removing the need for additional protective layers and their associated production costs
3Reliability
If a second insulating layer is formed to protect the active layer, then the active layer is protected, but productivity decreases
Solution Approach 1:
The patent removes the second insulating layer formation step entirely, reducing the total number of manufacturing steps. By designing the gate electrode to serve dual purposes (electrical control and protection), the invention eliminates a complete process step including material deposition and mask alignment, thereby improving productivity
Solution Approach 2:
Instead of adding a protective layer over the active layer, the invention inverts the approach by using the gate electrode structure itself as the protective element. This inversion eliminates the need for additional protective layers and their associated manufacturing steps, improving production efficiency
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 decreases the number of mask processes, lowers production costs, and enhances productivity by eliminating the need for the second insulating layer, while maintaining high mobility and constant current performance suitable for large-sized displays.
Implementation Method 1
oxidizing the exposed portion of the first metal pattern to form an oxide layer
Data Source
AI summary
An array substrate for a liquid crystal display device includes a substrate; a semiconductor layer on the substrate; a gate electrode on the semiconductor layer; source and drain electrodes that are on and contact the semiconductor layer; and an oxide layer that corresponds to the semiconductor layer and is on the gate electrode.