Poly-Si TFT LCD Fabrication Reducing Mask Count
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Solution Overview
Problem
The production of driving circuit-integrated LCD devices using poly-Si TFTs is complex and costly due to the need for multiple photolithography processes, which decreases production yield and increases the probability of defects and mask costs.
Innovation Solution
A method of fabricating LCD devices that simplifies the process by forming active patterns, gate electrodes, and source/drain regions on a substrate, using a reduced number of masks, including the option of a single mask process for forming source/drain and pixel electrodes, thereby reducing the complexity and cost of the production process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple photolithography processes are used to form active patterns, gate electrodes, and source/drain regions, then the driving circuit can be integrated on the array substrate, but the production process becomes complex and costly with decreased production yield
Solution Approach 1:
The patent combines the formation of active patterns, gate electrodes, and source/drain regions into a single photolithography process step. The mask is designed to simultaneously define all these features, eliminating the need for multiple sequential photolithography processes and their associated alignment steps, thereby simplifying the production process while maintaining driving circuit integration capability
Solution Approach 2:
The single mask serves multiple functions by simultaneously defining active patterns, gate electrodes, and source/drain regions. This multi-functional mask design allows one photolithography process to accomplish what traditionally required multiple separate processes, reducing production complexity and cost
2Manufacturing precision
If multiple photolithography processes are used, then precise patterning can be achieved, but the number of masks increases production cost and defect probability
Solution Approach 1:
Multiple patterning functions are merged into a single mask design, reducing the total number of masks required from multiple to just one. This consolidation maintains patterning precision for all features (active patterns, gates, source/drain) while eliminating the cumulative costs and defect risks associated with multiple separate photolithography steps
3Area of moving object
If the area of storage capacitors in pixels is reduced to improve aperture ratio, then more pixel area is available for light transmission, but the storage capacitor capacity may be insufficient
Solution Approach 1:
The patent extends storage capacitors into the circuit unit region outside the pixel array, utilizing the peripheral area that would otherwise be unused. This spatial relocation allows pixel-area storage capacitors to maintain sufficient capacity while minimizing their footprint within the pixel region, thereby improving aperture ratio without sacrificing storage capability
Data Source
AI summary
An LCD device and a method of fabricating the same are provided. The LCD device comprises a first substrate divided into a pixel unit and a circuit unit. Active patterns are disposed in the pixel unit and the circuit unit of the first substrate. A first insulating film is disposed on the first substrate. Gate electrodes are disposed in the pixel unit and the circuit unit of the first substrate, and common lines are disposed in the pixel unit of the first substrate. First contact holes and second contact holes are disposed in regions of the first insulating film, the first interlayer insulating film and the second interlayer insulating film. Source electrodes and drain electrodes electrically connect to the source regions and the drain regions of the active patterns through the first contact holes and the second contact holes.