TFT Substrate with Overlapping Color Filters for Light Shielding
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Solution Overview
Problem
Existing methods for thin film transistor (TFT) substrates, particularly those using oxide semiconductor channel layers, face issues with light-shielding and adhesive problems, leading to reduced productivity and increased costs due to the need for additional photoengraving processes and potential peeling of color filter layers.
Innovation Solution
A TFT substrate configuration with overlapping coloring layers in three colors (red, green, and blue) forming a light-shielding layer, where the end parts of these layers overlap to provide adequate light-shielding for the channel layer, reducing the likelihood of peeling and allowing for the use of a single photoengraving mask, thereby increasing productivity and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light-shielding layer is disposed above the TFT to protect the oxide semiconductor channel layer from ultraviolet light, then the reliability of the TFT is improved, but the device complexity and manufacturing process complexity increase due to requiring additional photoengraving processes
Solution Approach 1:
The color filter layers (red, green, and blue coloring layers) are designed to serve dual functions: (1) providing color display functionality for the LCD, and (2) acting as a light-shielding layer to protect the oxide semiconductor channel layer from ultraviolet light. By making the color filter layers sufficiently thick (0.5-5.0 μm), they inherently provide UV shielding without requiring a separate light-shielding layer, thus resolving the technical contradiction.
Solution Approach 2:
The invention merges the color filter function and the light-shielding function into a single structure. The color filter layers are formed with sufficient thickness to simultaneously perform color filtering and UV protection, eliminating the need for separate light-shielding layers and reducing manufacturing process complexity.
2Area of moving object
If the color filter layers are made thin to maintain high aperture ratio, then the display quality is improved, but the light-shielding effect against ultraviolet light becomes insufficient
Solution Approach 1:
The invention optimizes the thickness parameter of the color filter layers to fall within the range of 0.5-5.0 μm. This specific thickness range provides sufficient UV shielding capability while maintaining high aperture ratio and display quality. By precisely controlling this parameter, both requirements are satisfied simultaneously.
3Productivity
If a single photoengraving mask is used for forming all color filter layers, then the productivity is improved and manufacturing cost is reduced, but the manufacturing precision may be compromised due to the different pattern requirements for each color layer
Solution Approach 1:
A single photoengraving mask is designed to form all three color filter layers (red, green, and blue) simultaneously. The mask pattern is configured such that one exposure process creates the patterns for all color layers, eliminating the need for multiple masks and exposures. This maintains manufacturing precision while significantly improving productivity.
Solution Approach 2:
The formation processes for the red, green, and blue color filter layers are merged into a single photoengraving step using one mask. This consolidation reduces the number of manufacturing steps and increases productivity without sacrificing the required pattern accuracy for each color layer.
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 configuration effectively provides light-shielding for the TFT channel layer, reduces the risk of peeling, and simplifies the manufacturing process by allowing the use of a single photoengraving mask, leading to improved display quality and reduced manufacturing costs.
Implementation Method 1
A lowermost layer of the coloring laminated body is the red coloring layer or the green coloring layer... effectively provides light-shielding for the TFT channel layer
Data Source
AI summary
A plurality of pixel electrodes disposed in a matrix are electrically connected with a plurality of first thin film transistors, respectively. Coloring layers in a plurality of colors overlap, in a plan view, with two or more pixel electrodes adjacent to each other in one direction among the plurality of pixel electrodes. Channel layers of the first thin film transistors are covered from above by a coloring laminated body including end parts of the respective coloring layers in at least two colors among the coloring layers in a plurality of colors, the end parts overlapping with each other in the plan view.