Active Matrix Substrate Dual-Layer Holes for TFT Stability
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Solution Overview
Problem
In liquid crystal display devices, impurities such as moisture easily infiltrate the organic insulating layer during manufacturing, leading to fluctuations in the characteristics of oxide semiconductor TFTs, particularly in high-resolution displays where the organic insulating layer is thicker, causing display failures and off-leak currents.
Innovation Solution
An active matrix substrate with a dual-layer hole structure is introduced, featuring through-holes in the inorganic insulating layer and bottomed holes in the organic insulating layer, allowing for efficient discharge of impurities, with the through-holes positioned inside the outer edge of the bottomed holes to enhance impurity removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the organic insulating layer is formed thickly to achieve sufficient flattening effect and load capacitance reduction, then the flattening quality and power consumption improvement are enhanced, but impurities such as moisture easily infiltrate into the organic insulating layer and cannot be discharged, causing TFT characteristic fluctuations
Solution Approach 1:
The patent forms openings in the inorganic insulating layer before final assembly, allowing impurities to be discharged during subsequent heating processes. This preliminary preparation of discharge pathways prevents impurity accumulation that would otherwise occur with thick organic insulating layers
Solution Approach 2:
The inorganic insulating layer is designed with a porous structure containing multiple openings that extend through the layer. These openings create controlled porosity that facilitates impurity discharge while maintaining the insulating function of the layer
2Manufacturing precision
If the organic insulating layer thickness is increased in high-resolution displays, then the flattening effect is improved, but the volume ratio of the organic insulating layer increases, making impurity influence more significant
Solution Approach 1:
The patent extracts impurities from the organic insulating layer by providing dedicated discharge pathways through the inorganic insulating layer. The openings allow impurities to be removed from the system, preventing their accumulation and negative effects on TFT characteristics
Solution Approach 2:
The inorganic insulating layer with its opening structure serves as an intermediary that both supports the thick organic insulating layer for flattening purposes and simultaneously provides impurity discharge pathways, mediating between the conflicting requirements
Data Source
AI summary
An active matrix substrate includes a substrate, a pixel TFT that is supported by the substrate, provided corresponding to each of a plurality of pixel areas, and includes an oxide semiconductor layer, an organic insulating layer disposed above at least the oxide semiconductor layer of the pixel TFT, and an inorganic insulating layer disposed in contact with an upper surface of the organic insulating layer on the organic insulating layer. The organic insulating layer and the inorganic insulating layer are provided with a plurality of dual-layer hole structure portions, each of the dual-layer hole structure portions includes a through-hole provided in the inorganic insulating layer and a bottomed hole provided in the organic insulating layer and positioned below the through-hole, and the through-hole is positioned on an inner side of an outer edge of the bottomed hole when viewed from a normal direction of the substrate.