LCD Fabrication Reducing Masks to Boost Yield
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Solution Overview
Problem
The existing LCD fabrication process requires multiple photolithography masking processes, which degrades production yield, increases the probability of defective thin film transistors (TFTs), and raises fabrication costs due to the need for numerous expensive masks.
Innovation Solution
A method for fabricating LCDs using a reduced number of masks, specifically forming a gate line and gate electrode, and patterning thin films to create transistors and pixel electrodes using a single mask in each of three masking processes, thereby reducing the overall number of masking steps from five to three.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple photolithography masking processes are used to fabricate the array substrate, then the TFT structure can be formed with high precision, but the production yield degrades and fabrication costs increase
Solution Approach 1:
The patent combines multiple masking processes into a reduced number of masking steps by using a simplified fabrication method where the gate line and gate electrode are formed together, and thin films are patterned in fewer steps, thereby reducing the number of masks required from five to three while maintaining TFT structure precision
Solution Approach 2:
The patent employs masks that serve multiple functions in the fabrication process, where a single mask is used to form both the gate line and gate electrode, and subsequent masks pattern multiple thin films simultaneously, increasing mask utility and reducing the total number of masks needed
2Manufacturing precision
If multiple photolithography masking processes are used to fabricate the array substrate, then the TFT structure can be formed with high precision, but the fabrication costs increase due to numerous expensive masks
Solution Approach 1:
The patent merges multiple masking operations into fewer steps, reducing the total number of expensive masks required from five to three, thereby lowering fabrication costs while maintaining the precision needed for TFT structure formation
Solution Approach 2:
The patent reduces dependency on expensive, durable masks by designing a process that requires fewer masks, effectively treating mask usage as a consumable resource that is minimized through process optimization
3Ease of manufacture
If multiple photolithography masking processes are used to fabricate the array substrate, then complete TFT formation is achieved, but the probability of defective TFTs increases
Solution Approach 1:
The patent combines multiple masking processes into fewer steps, reducing the number of times the substrate undergoes photolithography treatment, thereby minimizing cumulative process variations and defects while still achieving complete TFT formation
Solution Approach 2:
The patent skips intermediate masking steps by using a simplified fabrication method that forms multiple structures in fewer steps, reducing the overall process time and the number of opportunities for defects to occur during photolithography
Data Source
AI summary
A liquid crystal display and a fabricating method thereof are provided. The liquid crystal display includes a first substrate having a pixel portion and a pad portion; a gate line and a data line crossing each other to define the pixel portion at the pixel portion; a transistor adjacent to a crossing of the gate line and the data line, the transistor including a gate electrode, a source electrode and a drain electrode; an insulating layer above the source electrode and the drain electrode, the insulating layer exposing a lateral side of the drain electrode; a pixel electrode in contact with the lateral side of the drain electrode; a second substrate attached to the first substrate; and a liquid crystal layer between the first substrate and a second substrate.