Poly-Silicon TFT Fabrication via Integrated Gate and Sealant Design
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Solution Overview
Problem
The manufacturing process for poly-silicon liquid crystal display devices is complex and costly due to the intricate structure of thin film transistor substrates.
Innovation Solution
A simplified method for fabricating poly-silicon liquid crystal display devices involves using a seven-mask process to form thin film transistors with a double-layer gate structure and storage capacitors, and sealing the source/drain metal patterns within a sealant area to protect them, reducing the complexity and cost of production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional multi-mask process is used to form thin film transistors and storage capacitors, then the manufacturing precision and device performance are improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the formation of thin film transistors and storage capacitors into a single integrated structure. The storage capacitor is formed using the same active layer, gate electrode, and insulating film layers as the TFT, eliminating the need for separate capacitor fabrication steps. This merging of structures directly reduces the number of photomask steps required while maintaining manufacturing precision.
Solution Approach 2:
The gate electrode serves dual functions as both the TFT gate and the storage capacitor electrode. The insulating film between the gate and active layer serves as both the TFT gate insulator and the storage capacitor dielectric. This multi-functionality of existing components eliminates the need for additional dedicated capacitor structures and reduces overall process complexity.
2Ease of manufacture
If source/drain metal patterns are exposed outside the sealant area, then the ease of manufacture is improved, but the reliability and protection of the device deteriorates
Solution Approach 1:
The sealant structure is designed in advance to completely enclose the source and drain electrodes within the sealant area. By positioning the sealant to overlap and cover the metal patterns before final assembly, the electrodes are pre-protected from environmental damage and contamination, eliminating the need for additional protective layers or post-processing steps.
3Duration of action of moving object
If the storage capacitor has high capacitance for stable video signal, then the duration of action is improved, but the device complexity increases
Solution Approach 1:
The storage capacitor shares the same physical layers and structures as the thin film transistor, including the active layer, gate electrode, and insulating films. This integrated approach achieves high capacitance values without requiring separate, complex capacitor structures, thereby maintaining signal stability while avoiding additional manufacturing complexity.
Data Source
AI summary
A poly-silicon liquid crystal display and a simplified method of fabricating the same are disclosed. A liquid crystal display device according to the present invention includes first and second substrates having a display region and a driver region; a first sealant overlapping the driver region; and a liquid crystal layer between the first and second substrates.