Thin Film Transistor Array Panel with Localized Organic Insulator Thickness
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Solution Overview
Problem
In liquid crystal displays (LCDs) with a structure where pixel electrodes and color filters are formed on different panels, alignment errors can occur, leading to non-uniform cell gaps and deteriorated contact characteristics due to the steep step shape between layers, causing material diffusion and obstruction of contact holes.
Innovation Solution
A thin film transistor array panel design featuring an insulation substrate with a signal line, thin film transistor, color filter, and organic insulator with varying thicknesses, along with a light blocking member formed on the organic insulator, maintaining a uniform cell gap and preventing contact hole obstruction by controlling the organic layer height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the organic layer is made relatively thin to prevent material diffusion, then material diffusion is reduced, but the edge of the color filter cannot be properly covered due to the steep step shape
Solution Approach 1:
The organic layer is designed with different thicknesses in different regions: a first thickness in the first region and a second thickness (greater than the first) in the second region. This local variation allows the organic layer to properly cover the steep step at the color filter edge while maintaining sufficient thickness control to prevent material diffusion in other areas.
2Manufacturing precision
If the organic layer is made relatively thick to ensure complete coverage, then coverage is improved, but excess material remains when forming contact holes, deteriorating contact characteristics
Solution Approach 1:
The organic layer thickness is locally optimized: thicker in the second region to ensure complete coverage of the color filter and light blocking member, and thinner in the first region to prevent excess material accumulation that would obstruct contact holes. This spatially differentiated thickness design simultaneously achieves both coverage and contact quality.
Solution Approach 2:
The organic layer is divided into multiple regions with different thickness characteristics. The first region has a first thickness suitable for contact hole formation, while the second region has a second thickness suitable for complete coverage. This segmentation allows each region to be optimized for its specific function without compromising the other.
3Manufacturing precision
If the light blocking member protrudes upward to ensure proper positioning, then positioning is improved, but the cell gap becomes non-uniform and the average cell gap is reduced
Solution Approach 1:
The organic layer serves as a positioning structure with locally varied thickness that supports the light blocking member at the appropriate height. The thicker second region provides adequate support and positioning while the controlled thickness variation ensures the light blocking member does not protrude excessively, thereby maintaining uniform cell gap across the display panel.
Data Source
AI summary
A thin film transistor array panel includes an insulation substrate. A signal line is formed on the insulation substrate. A thin film transistor is connected to the signal line. A color filter is formed on the substrate. An organic insulator is formed on the color filter and includes a first portion and a second portion having different thicknesses. A light blocking member is formed on the second portion of the organic insulator. A difference between the surface height of the first portion of the organic insulator and the surface height of the second portion of the organic insulator is in the range of about 2.0 μm to 3.0 μm.