IGZO Array Substrate Dual-Active Layer Structure for High Mobility
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Solution Overview
Problem
Hydrogenated amorphous silicon TFTs face challenges in achieving high mobility and brightness in large-size LCDs, leading to increased power consumption and complexity due to the opaque nature of the a-Si material and the need for opaque metal masks, which reduces aperture ratio and reliability.
Innovation Solution
A method for fabricating an array substrate with a dual-active layer structure using indium gallium zinc oxide (IGZO) or similar materials, involving multiple patterning processes to form active layers, source/drain regions, common electrodes, and pixel electrodes, which improves on-state current and reduces pixel charging time, while minimizing material and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If amorphous silicon material is used for forming large-size LCD devices at low temperatures, then manufacturing cost and complexity are reduced, but the material is opaque to visible light requiring opaque metal masks or black matrices which increases device complexity and reduces aperture ratio
Solution Approach 1:
The patent extracts and removes the opaque metal mask or black matrix layer from the device structure by using transparent conductive oxide materials for both the active layer and the conductive layer, thereby eliminating the need for light-blocking components and reducing overall device complexity
Solution Approach 2:
The patent changes the optical parameter (transparency) of the conductive materials by transitioning from opaque amorphous silicon to transparent conductive oxides, allowing light to pass through the active layer without requiring additional opaque masking layers
2Ease of manufacture
If amorphous silicon material is used for forming large-size LCD devices at low temperatures, then manufacturing cost and complexity are reduced, but aperture ratio is reduced due to the need for opaque metal masks or black matrices
Solution Approach 1:
The patent removes the opaque metal mask or black matrix layer from the device structure by using transparent conductive oxide materials, thereby increasing the light-transmissive area and aperture ratio
Solution Approach 2:
The patent changes the optical parameter (transparency) of the conductive materials, allowing light to pass through the active layer and conductive layer without being blocked, thereby increasing the effective aperture ratio
3Illumination intensity
If light intensity is increased to obtain sufficient brightness, then brightness is improved, but power consumption of the display device is increased
Solution Approach 1:
The patent changes the electrical parameter (mobility) of the semiconductor material by using transparent conductive oxide materials with higher carrier mobility, enabling more efficient charge transport and reducing the power required to achieve sufficient brightness
Solution Approach 2:
The patent uses composite material structures with transparent conductive oxide layers configured to provide both electrical conductivity and optical transparency, enabling efficient light transmission and charge transport while maintaining low power consumption
4Reliability
If hydrogenated amorphous silicon semiconductor mobility is increased, then device performance is improved, but it is difficult to exceed 1cm2/Vs mobility limit
Solution Approach 1:
The patent changes the fundamental material parameter (carrier mobility) by transitioning from hydrogenated amorphous silicon to transparent conductive oxide materials, achieving mobility values significantly higher than the 1cm2/Vs limit of a-Si
Solution Approach 2:
The patent employs transparent conductive oxide materials with inherently higher mobility characteristics, providing superior charge transport properties and enabling high-performance display devices with improved reliability and responsiveness
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 dual-active layer structure enhances the on-state current and reduces pixel charging time, benefiting large-size displays with high pixels-per-inch and high frequency, while ensuring low cost and performance stability, and reduces power consumption by optimizing the conductive layer formation.
Implementation Method 1
The second portion of the first oxide layer is converted into the conductive layer by a plasma
Implementation Method 2
The second portion of the first oxide layer is converted into the conductive layer by an ion implantation process
Data Source
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Figure 7~8
AI summary
An array substrate and fabricating method thereof, a display panel, and a display apparatus are provided. A first active layer (120a) and common electrodes (125) are formed on the substrate (110). A first gate insulating layer (130a) is formed on the first active layer (120a). A gate electrode (140a) is formed on the first gate insulating layer (130a). A second gate insulating layer (160) is formed on the common electrodes (125) and the gate electrode (140a). Via-holes (165) are formed in the second gate insulating layer (160) to expose surface portions of the common electrodes (125). Source/drain electrodes (170s/d) are formed and electrically connected to the common electrodes (125) through the via-holes (165). A second active layer (180a) and pixel electrodes (185) are formed on the second gate insulating layer (160).