Three-Layer Active Layer Structure for Liquid Crystal Display Leakage Reduction
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Solution Overview
Problem
Large-sized and high-resolution liquid crystal display devices face issues with electric leakage due to poor homogeneity and interfacial defects in the backchannel, leading to uneven luminance and reliability problems, primarily caused by the high-speed deposited film layer's poor film quality and interface-state density.
Innovation Solution
A liquid crystal display panel with a three-layer active layer structure, where a second film layer is formed between a low-speed and high-speed deposited film layer, ensuring the passivation layer contacts the second film layer, which has better film quality and interface-state density, reducing leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high-speed deposited film layer (AH) is used in the active layer, then the deposition speed is improved and productivity is increased, but the film quality deteriorates and interfacial defects increase, leading to high leakage current
Solution Approach 1:
The active layer is segmented into three distinct film layers: a low-speed deposited film layer (AL) with good quality, a medium-speed deposited film layer (AL2) with intermediate properties, and a high-speed deposited film layer (AH) with high deposition speed. This segmentation allows each layer to contribute different characteristics, with the AL and AL2 layers providing good interface quality where they contact the passivation layer, while the AH layer provides high-speed deposition for the bulk of the active layer thickness.
Solution Approach 2:
Different regions of the active layer are assigned different deposition speeds based on their functional requirements. The regions contacting the passivation layer (AL and AL2 layers) use low-to-medium deposition speeds to ensure good film quality and low interface-state density, while the upper region (AH layer) uses high deposition speed. This local differentiation of quality characteristics resolves the contradiction between overall productivity and local film quality.
2Device complexity
If a two-layer active layer structure (AL/AH) is used, then the manufacturing process is simplified, but the backchannel homogeneity deteriorates and leakage current increases
Solution Approach 1:
The active layer is divided into three layers (AL, AL2, AH) instead of two, with the intermediate AL2 layer serving as a transition zone. This segmentation creates a more gradual transition in deposition speed and film properties, improving backchannel homogeneity. The AL and AL2 layers ensure good interface quality with the passivation layer, while the AH layer provides efficient charge transport, collectively reducing leakage current and improving reliability.
Solution Approach 2:
The active layer is constructed as a composite structure combining three different film types with distinct deposition characteristics. The low-speed AL layer provides excellent interface quality, the medium-speed AL2 layer provides transition and additional quality, and the high-speed AH layer provides efficient charge transport. This composite structure achieves both good backchannel homogeneity and low leakage current while maintaining reasonable manufacturing complexity.
3Ease of manufacture
If the passivation layer contacts the high-speed deposited film layer (AH), then the manufacturing process is simplified, but the interface-state density increases and leakage current rises
Solution Approach 1:
The active layer is segmented so that the passivation layer contacts the low-speed AL layer and medium-speed AL2 layer, but not the high-speed AH layer. This segmentation ensures that the critical passivation layer interface is formed with layers having low interface-state density, while the high-speed AH layer is positioned away from this critical interface, thus reducing leakage current without significantly complicating the manufacturing process.
Solution Approach 2:
The AL and AL2 layers serve as intermediary layers between the passivation layer and the high-speed AH layer. These intermediary layers have good film quality and low interface-state density, acting as buffers that protect the critical passivation layer interface from the poorer quality AH layer. This intermediary structure allows the use of high-speed deposition for the AH layer while maintaining good interface characteristics where the passivation layer contacts the active layer.
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
The three-layer active layer structure improves backchannel characteristics and reduces electric leakage, resulting in better display performance and uniformity.
Implementation Method 1
AL is a main electrically-conductive channel, and is formed at a low speed... AH, formed at a high speed
Data Source
AI summary
Disclosed is a liquid crystal display panel and a method for manufacturing the same. The panel includes a thin-film transistor. An active layer in communication with a source and a drain of the thin-film transistor is formed by more than two film layers. The active layer contacts with a passivation layer of the panel on a non-high-speed deposited film layer of the active layer.