Mask Light Shielding Pattern for TFT Channel Uniformity
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Solution Overview
Problem
The fabrication of small-sized thin film transistors (TFTs) in display devices is prone to defects due to errors in the fabrication process, particularly in forming the channel region, which can lead to variations in width and signal transmission issues.
Innovation Solution
A mask with a light shielding pattern and auxiliary light shielding portions is used to prevent over-exposure during the light exposure process, ensuring precise definition of the channel boundaries by including semi-transmissive portions and protrusions at the ends of the source and drain electrodes, thereby maintaining uniformity and preventing concave portions in the channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional mask is used to form small-sized TFT channels, then the fabrication process is simple, but defects occur due to over-exposure and variations in channel width
Solution Approach 1:
The mask's light shielding pattern is segmented into multiple functional regions: light transmitting portions for precise pattern definition, semi-transmissive portions for controlled light exposure to prevent over-exposure, and auxiliary light shielding portions to block stray light. This segmentation enables precise channel width control while managing the complexity through functional differentiation of mask regions.
Solution Approach 2:
Different regions of the mask are assigned different optical properties: the light transmitting portions have high transparency for precise pattern formation, the semi-transmissive portions provide reduced light transmission to prevent over-exposure, and the auxiliary light shielding portions block stray light. This local differentiation of optical qualities resolves the contradiction by tailoring each region's properties to its specific functional requirements.
2Reliability
If the channel region is formed with precise boundaries, then signal transmission quality improves, but the light exposure process becomes more sensitive to errors
Solution Approach 1:
The semi-transmissive portions act as an intermediary layer between the light source and the photoresist, providing controlled light transmission that prevents over-exposure while maintaining precise pattern boundaries. This intermediary mechanism protects the delicate light exposure process from errors, ensuring reliable channel formation without requiring extremely high exposure control precision.
Solution Approach 2:
The auxiliary light shielding portions are positioned in advance to block stray light before it can cause unwanted exposure or interference. This preemptive shielding cushions the light exposure process against potential errors, ensuring that only the intended light paths affect the photoresist, thereby maintaining measurement precision and signal transmission quality.
3Manufacturing precision
If auxiliary light shielding portions are added to the mask, then over-exposure is prevented and channel uniformity is maintained, but the mask fabrication process becomes more complex
Solution Approach 1:
The auxiliary light shielding portions are merged with the main light shielding pattern as an integrated structure, formed in the same fabrication process steps. This merging approach combines the functional benefits of over-exposure prevention with the existing mask manufacturing workflow, reducing the practical impact on fabrication ease while maintaining high channel boundary definition precision.
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 helps in preventing defects in the channel formation of small-sized TFTs, ensuring high-resolution display quality by maintaining uniform channel width and preventing signal transmission errors.
Implementation Method 1
a light shielding pattern including a light transmitting portion and a light shielding portion on the base substrate
Implementation Method 2
including semi-transmissive portions and protrusions at the ends of the source and drain electrodes
Data Source
AI summary
A mask includes a base substrate, and a light shielding pattern including a light transmitting portion and a light shielding portion on the base substrate, wherein the light shielding portion includes a third source electrode portion, a third drain electrode portion spaced apart from the third source electrode portion and including at least a portion parallel to the third source electrode portion, a first auxiliary light shielding portion at an end portion of the third source electrode portion facing the third drain electrode portion, and a second auxiliary light shielding portion at an end portion of the third drain electrode portion facing the third source electrode portion.