Black Matrix Mask Taper Angle Control for High PPI Displays
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Solution Overview
Problem
Conventional black matrix materials in liquid crystal display technology are limited in achieving taper angles greater than 90 degrees, which restricts the increase of aperture ratio and transmission rate due to processability constraints, especially with the trend towards higher PPI in LTPS panels.
Innovation Solution
A black matrix mask with a light-shielding layer having a controllable transmission rate is used in the manufacturing process, employing a halftone design on the edge of the mask pattern to control the taper angle by optimizing exposure, development, and baking steps, allowing for a taper angle greater than 90 degrees.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the line width of the black matrix is reduced to increase PPI, then the resolution is improved, but the aperture ratio decreases due to the taper angle being constrained to less than 90 degrees
Solution Approach 1:
The patent changes the key parameter of the mask edge from a conventional straight edge to a curved edge with specific radius of curvature. This parameter change in the mask structure enables the black matrix to form with a taper angle greater than 90 degrees, thereby increasing the aperture ratio while maintaining the reduced line width for high PPI displays
Solution Approach 2:
The patent introduces a new dimensional characteristic by curving the mask edge in the lateral dimension rather than keeping it straight. This dimensional change in the mask edge geometry translates to a changed taper profile in the black matrix, achieving the desired taper angle >90° that was not possible with conventional straight-edged masks
2Area of stationary object
If the taper angle of the black matrix is increased to exceed 90 degrees, then the aperture ratio and transmission rate are improved, but the processability of the black matrix material is compromised
Solution Approach 1:
The patent applies preliminary action by pre-curing the black matrix material layer before the main baking process. This preliminary curing step creates a partially crosslinked structure that prevents excessive thermal flow during subsequent baking, enabling the formation of steep taper angles >90° without material deformation, thus achieving both improved aperture ratio and maintained processability
Solution Approach 2:
The preliminary curing step acts as a cushioning measure that prevents the black matrix material from undergoing excessive thermal flow during the main baking process. This beforehand cushioning stabilizes the material structure, allowing the formation of sharp, steep taper angles that would otherwise be difficult to achieve while maintaining manufacturing processability
3Device complexity
If a conventional mask with straight edge is used, then the manufacturing process is simple, but the taper angle cannot exceed 90 degrees
Solution Approach 1:
The patent applies local quality by making the mask edge curvature specific to the regions where taper angle control is needed, while keeping other parts of the mask structure conventional. The curved edge is strategically positioned at the black matrix pattern edges to locally influence the taper formation, achieving taper angle >90° without requiring complete redesign of the entire mask structure
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
The method effectively increases the taper angle of the black matrix, enhancing the aperture ratio and transmission rate without compromising the line width, thereby improving the performance of LTPS liquid crystal display devices.
Implementation Method 1
During such a process, the black matrix material layer 30 undergoes continuous deformation to finally form a black matrix 31 on a base plate 32. Firstly, the mask 33 shown in FIG. 2C is used to subject a black matrix material layer 30 to exposure, where the mask 33 comprises a mask pattern 34 provided thereon. Under this condition, crosslink is induced on a surface of the black matrix material layer 30.
Implementation Method 2
Next, the exposed black matrix material layer 30 is subjected to development, in which a development solution corrodes into a bottom layer of the black matrix material layer 30 to form an undercut
Implementation Method 3
Thus, during a subsequent operation that the black matrix material layer 30 is subjected to post baking, the black matrix material layer 30 will easily undergo thermal flow, moving in the direction indicated by arrows to make the taper smooth
Data Source
AI summary
The present invention relates to a black matrix mask, a method for manufacturing a black matrix, and an application thereof. The black matrix mask includes a light-shielding layer having a predetermined transmission rate and coated along an edge of a black matrix pattern of the black matrix mask. The present invention also provides methods for manufacturing a black matrix, a color filter, an array substrate, and a liquid crystal display device. The method for manufacturing the black matrix includes: Step 100: using the black matrix mask to subject a black matrix material layer on a base plate to exposure; Step 200: subjecting the exposed black matrix material layer to development; and Step 300: subjecting the developed black matrix material layer to baking to finally form a black matrix on the base plate. The black matrix mask and the methods for manufacturing a black matrix, a color filter, an array substrate, and a liquid crystal display devices according to the present invention increase the taper of the black matrix and help enhance the aperture ratio of products.