Oxide Semiconductor Top-Gate TFT for Large-Size Display Manufacturing
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Solution Overview
Problem
The complexity and high costs associated with manufacturing large-size liquid crystal displays using amorphous silicon thin film transistors, which require multiple patterning processes and a passivation layer, hinder efficiency and aperture ratio.
Innovation Solution
A top-gate type array substrate with an oxide semiconductor active layer, such as IGZO, IZO, or ZnO, is fabricated using three patterning processes, eliminating the need for a passivation layer and simplifying the manufacturing process, thereby reducing costs and improving mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If amorphous silicon thin film transistor is used, then the display device can be manufactured with mature technology, but the process complexity increases and aperture ratio decreases due to the need for black matrix and multiple patterning processes
Solution Approach 1:
The patent changes the material parameter from amorphous silicon to oxide semiconductor, which fundamentally alters the electrical properties and enables a top-gate transistor structure. This material substitution eliminates the need for black matrix and reduces the number of patterning processes from four or more to three, directly resolving the contradiction between ease of manufacture and device complexity
Solution Approach 2:
The patent inverts the conventional bottom-gate transistor structure to a top-gate structure. In the top-gate configuration, the gate electrode is positioned above the active layer instead of below, which simplifies the manufacturing process by eliminating the need for etching stop layers and passivation layers, thereby reducing process complexity while maintaining ease of manufacture
2Temperature
If amorphous silicon thin film transistor is used, then the display device can be manufactured at low temperature, but the mobility is insufficient for high-frequency drive circuits
Solution Approach 1:
The patent changes the material composition from amorphous silicon to oxide semiconductor (such as IGZO, IZO, or ZnO), which fundamentally improves the carrier mobility from approximately 0.5 cm²/Vs to significantly higher values. This material parameter change enables the transistor to meet the mobility requirements for high-frequency drive circuits while maintaining low-temperature manufacturing capability
3Reliability
If oxide semiconductor thin film transistor with bottom-gate type is used, then high mobility is achieved, but the process complexity increases due to at least four patterning processes and additional protection layers
Solution Approach 1:
The patent inverts the bottom-gate structure to a top-gate structure, which fundamentally simplifies the manufacturing process. The top-gate configuration eliminates the need for etching stop layers and passivation layers that are required in bottom-gate structures, reducing the number of patterning processes from four or more to three, thereby achieving high mobility with reduced process complexity
Solution Approach 2:
The patent extracts and removes the unnecessary protection layers (etching stop layer and passivation layer) from the manufacturing process. By adopting the top-gate structure, these protective layers are no longer needed, as the gate electrode itself provides sufficient protection during subsequent processing steps, thereby simplifying the overall process
4Object-affected harmful factors
If black matrix is added to block light in amorphous silicon TFT, then light sensitivity is controlled, but the aperture ratio and reliability decrease
Solution Approach 1:
The patent changes the active layer material from amorphous silicon to oxide semiconductor, which fundamentally alters the optical properties. Oxide semiconductors have different light sensitivity characteristics that do not require the black matrix for light blocking, thereby eliminating the need for this additional layer and increasing the aperture ratio while maintaining proper light sensitivity control
Data Source
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AI summary
The embodiments of the invention provide a display device, a thin film transistor, an array substrate and a manufacturing method thereof. The manufacturing method comprises: step A, forming patterns of a source electrode, a drain electrode, a data line and a pixel electrode; step B, forming an active layer and agate insulating layer in order, and forming a via hole in the gate insulating layer for connecting the data line and an external circuit; and step C, forming patterns of a gate electrode, a gate line and a common electrode line, or forming a pattern of a gate electrode, a gate line and a common electrode.