Thin Film Transistor Substrate With Protective Film Slits
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Solution Overview
Problem
The manufacturing process for thin film transistor substrates in liquid crystal displays is complex and costly due to the need for multiple masking processes, with existing four-mask and five-mask processes still being expensive and time-consuming.
Innovation Solution
A three-mask process using a lift-off method is introduced, which includes forming pad electrodes, a protective film with slits for improved stripper infiltration, and a transparent conductive film patterned using a photo-resist pattern to simplify the process and reduce costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple masking processes are used to form thin film transistor substrate, then manufacturing precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies preliminary action by forming the photo-resist pattern before depositing the transparent conductive film. This sequence allows the photo-resist to serve as a sacrificial mask that defines the electrode patterns, eliminating the need for separate masking processes. The transparent conductive film is deposited over the photo-resist pattern, and subsequent lift-off removes the photo-resist along with excess film material, achieving precise pattern formation in advance of the final structure creation.
Solution Approach 2:
The patent extracts the masking function from the traditional multi-step photolithography process and replaces it with a lift-off process. The photo-resist pattern is used temporarily to define patterns during deposition, then completely removed after serving its purpose. This extraction of the masking step eliminates the complexity of multiple masking processes while maintaining manufacturing precision through the lift-off mechanism.
2Manufacturing precision
If multiple masking processes are used to form thin film transistor substrate, then manufacturing precision is improved, but loss of time increases
Solution Approach 1:
The patent merges multiple separate processes into a single integrated flow. The photo-resist pattern formation, transparent conductive film deposition, and pattern definition are combined into one continuous process sequence. The lift-off step simultaneously removes the photo-resist and excess film material in one operation, rather than requiring separate etching and cleaning steps, thereby reducing manufacturing cycle time while maintaining precision.
Solution Approach 2:
The patent skips the traditional intermediate steps of masking, aligning, and multiple exposure processes by using the lift-off method. The photo-resist pattern directly guides the film deposition, and the lift-off process rapidly removes unnecessary materials without requiring precise alignment steps, thus rushing through the pattern formation process efficiently while maintaining high precision.
3Stability of the object's composition
If photo-resist pattern is used without slits in protective film, then protective film integrity is maintained, but lift-off ability deteriorates
Solution Approach 1:
The patent applies local quality by introducing slits only in specific locations within the protective film where lift-off is required, rather than compromising the entire film structure. The slits are localized to areas adjacent to pad electrodes where stripper infiltration is needed, while the rest of the protective film maintains its integrity and protective function. This localized modification enables effective lift-off without sacrificing overall film stability.
Solution Approach 2:
The slits in the protective film serve as intermediaries that facilitate the action of the stripper solution. The slits provide pathways for the stripper to infiltrate between the photo-resist pattern and the protective film, enabling the lift-off process. The slits themselves are not part of the final structure but mediate the removal process, allowing the stripper to access the interface between layers and enable clean separation.
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 simplifies the semiconductor manufacturing process, reduces manufacturing costs, and enhances the lift-off ability of the photo-resist pattern, thereby improving production efficiency and yield.
Implementation Method 1
forming a slit in the protective film adjacent to at least one of the plurality of pad electrodes
Data Source
AI summary
A thin film transistor substrate for a display device having a plurality of thin film transistors and pixel electrodes connected to the thin film transistors, said thin film transistor substrate includes: a plurality of pad electrodes in a non-display area of the display device for applying signals to the plurality of thin film transistors in a non-display area of the display device; a protective film covering the pad electrodes in the non-display area; and a slit in the protective film adjacent to at least one of the plurality of pad electrodes.