Liquid Crystal Display Device with Inorganic Protective Films
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Solution Overview
Problem
The existing liquid crystal display (LCD) manufacturing process is complex and costly due to the need for multiple masks and the use of photo active compounds (PAC), which leads to increased fabrication time and yield deterioration because of the different materials used for the first and second protective films.
Innovation Solution
A liquid crystal display device with a COT (color filter on TFT) structure is fabricated using ten masks, where inorganic protective films are used for all layers, including the pixel electrodes and common electrodes, and column spacers, eliminating the need for photo active compounds and simplifying the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photo active compounds (PAC) and multiple masks are used in the manufacturing process, then the liquid crystal display device can be fabricated with proper layer formation, but the fabrication process becomes complex and costly with increased fabrication time and yield deterioration
Solution Approach 1:
The patent extracts and removes the photo active compound (PAC) layer from the manufacturing process. By eliminating this organic layer, the complex multi-mask process is simplified while maintaining the ability to form proper device layers through alternative means
Solution Approach 2:
The patent merges the functions of multiple separate masks and material deposition steps into a simplified process. The inorganic protective films serve multiple purposes simultaneously, reducing the total number of fabrication steps required
2Reliability
If different materials are used for the first and second protective films, then the device can achieve proper functional performance, but the manufacturing process requires separate mask processes for different materials increasing complexity and cost
Solution Approach 1:
The patent uses the same inorganic material for both the first and second protective films, creating homogeneity in material composition. This allows both layers to be processed identically through the same mask and deposition steps, eliminating the need for separate processing sequences
3Manufacturing precision
If multiple masks are used for fabricating the liquid crystal display device, then proper pattern formation can be achieved, but the fabrication time increases and productivity decreases
Solution Approach 1:
The patent performs preliminary actions by forming the inorganic protective films and integrating their patterning steps early in the process. The first and second protective films are patterned together in coordinated steps, preventing the need for separate subsequent mask operations
Solution Approach 2:
The patent combines multiple patterning operations into integrated process steps. The first and second protective films are formed and patterned in a merged sequence rather than as separate operations, reducing total fabrication time
Data Source
AI summary
A liquid crystal display device includes a first substrate having a thin film transistor (TFT) in each pixel region, a first inorganic protective film on the first substrate including the TFT, color filters on the first inorganic protective film in each pixel region excluding the TFT, a common electrode on the color filters, a second protective film over the entire first inorganic protective film including the common electrode, a pixel electrode on the second inorganic protective film with the pixel electrode connected to a drain electrode of the TFT exposed by selective removal of the first and second inorganic protective films, the pixel electrode forming a fringe field with the common electrode such that the second inorganic protective film is interposed between the pixel electrode and the common electrode, and a column spacer on the second inorganic protective film with the column spacer covering the TFT.