Active Matrix Substrate Insulating Layer Stack for Liquid Crystal Display
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Solution Overview
Problem
The use of multilayer structures in inorganic and gate insulating layers in liquid crystal display panels can lead to color shifts and tinge variations during oblique observation due to in-plane variations in layer thickness, which become more significant as mother substrate sizes increase.
Innovation Solution
Incorporating an intermediate layer with a refractive index between that of silicon oxide and silicon nitride layers in the multilayer structure of the insulating layers to reduce optical interference and minimize tinge variations, specifically using a silicon oxynitride layer as the intermediate layer to achieve the desired refractive index range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multilayer structure including silicon oxide layer and silicon nitride layer is used for gate insulating layer or inorganic insulating layer, then the reliability of oxide semiconductor TFT is improved, but tinge variation and color shift occur due to in-plane thickness variation
Solution Approach 1:
An intermediate layer with refractive index between silicon oxide and silicon nitride is introduced as a mediator in the insulating layer stack. This intermediate layer optically compensates for thickness variations in the multilayer structure, reducing interference color variations and tinge shifts while maintaining the electrical insulation and device reliability functions of the original multilayer configuration.
2Productivity
If mother substrate size is increased to increase production efficiency, then productivity is improved, but tinge variation becomes more significant
Solution Approach 1:
The refractive index parameter of the insulating layer stack is modified by introducing an intermediate layer with specific refractive index properties. This parameter change enables optical compensation for thickness variations that occur across large mother substrates, allowing increased substrate size and productivity without sacrificing white uniformity and display 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
This configuration significantly reduces tinge variations and improves white uniformity in liquid crystal display panels, allowing for larger mother substrates without compromising display quality.
Implementation Method 1
an in-plane variation in thickness of layers (insulating layers) constituting each of the inorganic insulating layer and the gate insulating layer is visually observed as a difference in interference color (which is caused by optical interference in the insulating layers)
Data Source
AI summary
An active matrix substrate according to an embodiment of the present invention includes a plurality of thin film transistors supported on a substrate and an inorganic insulating layer covering the plurality of thin film transistors. Each thin film transistor includes a gate electrode, an oxide semiconductor layer, a gate insulating layer, a source electrode, and a drain electrode. At least one of the gate insulating layer and the inorganic insulating layer is an insulating layer stack having a multilayer structure including a silicon oxide layer and a silicon nitride layer. The insulating layer stack further includes an intermediate layer disposed between the silicon oxide layer and the silicon nitride layer, the intermediate layer having a refractive index nC higher than a refractive index nA of the silicon oxide layer and lower than a refractive index nB of the silicon nitride layer.