TFT Substrate Fabrication via Merged Semiconductor and Transparent Conductive Layers
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Solution Overview
Problem
The fabrication process of thin film transistor substrates for liquid crystal display devices with horizontal electric field technology is complex and costly due to the requirement of multiple mask processes, which increases the manufacturing cost and complexity.
Innovation Solution
A three-step mask process is implemented to simplify the fabrication of thin film transistor substrates, involving the formation of a gate line, semiconductor layer, and source/drain metal pattern, with the semiconductor layer being removed from areas overlapping a transparent conductive film to reduce the number of mask processes and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple mask processes are used for fabricating thin film transistor substrate, then the liquid crystal display device can be produced, but the fabrication process becomes complex and costly
Solution Approach 1:
The patent combines the formation of the semiconductor layer and the transparent conductive film into a single deposition step, creating an integrated layer structure. This merging reduces the number of separate mask processes required, as both layers can be patterned together in fewer steps, thereby simplifying the fabrication process while maintaining device performance
Solution Approach 2:
The patent designs the semiconductor layer and transparent conductive film to serve multiple functions within the same structural framework. The integrated layer structure enables both layers to be processed simultaneously through single mask patterns, making the fabrication process more universal and efficient without compromising the individual functions of each layer
2Reliability
If multiple mask processes are used for fabricating thin film transistor substrate, then the liquid crystal display device can be produced, but the manufacturing cost increases
Solution Approach 1:
By merging the deposition of semiconductor layer and transparent conductive film into a single process step, the patent reduces the total number of mask processes required. This consolidation directly lowers manufacturing costs by reducing material waste, process time, and equipment usage while maintaining the functional integrity of both layers
Solution Approach 2:
The patent performs preliminary deposition of both the semiconductor layer and transparent conductive film in advance, before any patterning occurs. This preliminary action allows subsequent mask processes to pattern both layers simultaneously, reducing the total number of expensive mask steps required and lowering overall manufacturing costs
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 approach reduces the complexity and cost of manufacturing by minimizing the number of mask processes, improving productivity and material usage while maintaining the performance of the liquid crystal display devices with wide viewing angles.
Implementation Method 1
The liquid crystal 24 having a dielectric anisotropy is rotated in accordance with an electric field formed by a data signal on the pixel electrode 22 and a common voltage Vcom from the common electrode 8 to control light transmittance
Data Source
AI summary
A liquid crystal display device, including: first and second substrates; a gate line on the first substrate; a data line crossing the gate line defining a pixel area with a gate insulating film therebetween; a thin film transistor including a gate electrode, a source electrode, a drain electrode, and a semiconductor layer with a channel between the source electrode and the drain electrode; a common line in parallel to the gate line on the first substrate; a common electrode extending from the common line into the pixel area; and a pixel electrode on the gate insulating film in the pixel area, wherein the drain electrode overlaps with the pixel electrode to connect to the pixel electrode; and wherein the semiconductor layer is removed from an area where it overlaps a transparent conductive film.