Oxide TFT Contact Structure to Prevent Etch-Hole Projections
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Solution Overview
Problem
In top-gate type oxide semiconductor TFT substrates, the formation of projections in contact holes during the etching process can lead to reduced coverage of the protective insulating layer, causing moisture or hydrogen to enter the active layer and potentially degrade the TFT performance by increasing the risk of conduction between the source and drain.
Innovation Solution
The active matrix substrate incorporates a layered structure for the gate and connection electrodes, including a Cu-containing conductive layer and a metal oxide layer identical to the oxide semiconductor layer, which suppresses the formation of projections during etching by acting as an etching inhibitor, ensuring better coverage of the protective insulating layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a contact hole exposing a part of the first wiring line is formed in the interlayer insulating layer, then electrical connection between gate metal layer and source metal layer is achieved, but a projection made of interlayer insulating layer material is formed in the contact hole reducing protective insulating layer coverage
Solution Approach 1:
A metal oxide layer is introduced as an intermediary substance between the interlayer insulating layer and the protective insulating layer. This metal oxide layer fills the contact hole and serves as a mediator that prevents the formation of projections of interlayer insulating layer material, thereby ensuring proper coverage of the protective insulating layer while maintaining electrical connection functionality.
Solution Approach 2:
The chemical composition and physical properties of the contact hole filling material are changed from interlayer insulating layer material to metal oxide material. This parameter change prevents projection formation and improves the coverage of the protective insulating layer, solving the manufacturing precision issue while maintaining electrical connectivity.
2Reliability
If protective insulating layer coverage is reduced due to projection formation, then moisture and hydrogen can enter the active layer, but TFT performance degradation is prevented by proper coverage
Solution Approach 1:
The metal oxide layer acts as an intermediary barrier that prevents moisture and hydrogen from reaching the active layer through the contact hole region. By filling the contact hole and providing a smooth surface, it eliminates the projection that would otherwise compromise the protective insulating layer coverage, thereby preventing harmful substance ingress and maintaining TFT performance stability.
Solution Approach 2:
The potential harm of having an exposed surface in the contact hole region is converted into a benefit by intentionally filling it with metal oxide material. This transformation creates a protective barrier that prevents moisture and hydrogen ingress, turning what could be a vulnerability into a protective feature that enhances TFT reliability.
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 solution effectively prevents the degradation of oxide semiconductor TFTs by reducing the formation of projections, maintaining the integrity of the insulating layer and preventing moisture and hydrogen ingress, thereby enhancing the reliability and performance of the TFTs.
Implementation Method 1
a metal oxide layer disposed on the Cu-containing conductive layer... which suppresses the formation of projections during etching by acting as an etching inhibitor
Data Source
AI summary
An active matrix substrate includes a plurality of oxide semiconductor TFTs, and a plurality of wiring line connection sections, each of the plurality of wiring line connection sections includes a first connection electrode, an interlayer insulating layer extending over the first connection electrode, a wiring line contact hole formed in an insulating layer including the interlayer insulating layer, the wiring line contact hole exposing a part of a metal oxide layer of a first connection electrode, and a second connection electrode, and the second connection electrode is connected to a part of the metal oxide layer of the first connection electrode in the wiring line contact hole.