Display Substrate Planarizing Layer Height Difference
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Solution Overview
Problem
Conventional display substrate manufacturing processes often result in a height difference between the black matrix and the color filter, leading to an unsmooth surface, decreased product yield, and poor display quality due to non-uniform rubbing during alignment layer application.
Innovation Solution
A planarizing layer, made of opaque or transparent photoresist or resin, is formed on the black matrix and/or color filter to minimize the height difference between the two, using a lithography process with a gray tone mask to ensure the upper surface of the planarizing layer is flush with the color filter, thereby improving surface smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional manufacturing process is used to form the black matrix and color filter, then the manufacturing process is simple, but a height difference is produced between the black matrix and color filter resulting in an unsmooth surface
Solution Approach 1:
A planarizing layer is formed in advance on the black matrix before subsequent manufacturing steps. This preliminary action fills the height difference between the black matrix and color filter, creating a smooth surface that prevents defects in later processes while maintaining overall process simplicity
Solution Approach 2:
The planarizing layer acts as an intermediary element between the black matrix and subsequent films. It mediates the height difference issue by providing a transition layer that eliminates surface irregularities, allowing smooth deposition of alignment layers and other subsequent films without direct contact with the stepped surface
2Productivity
If other films are deposited on the black matrix and color filter with height difference, then the film deposition process is completed, but the surface of the display substrate becomes unsmooth and product yield decreases
Solution Approach 1:
The planarizing layer is applied before depositing subsequent films such as alignment layers. This preliminary smoothing action ensures that when films are deposited later, they land on a uniform surface, preventing non-uniform rubbing and defects that would reduce product yield
Solution Approach 2:
The planarizing layer serves as a cushioning layer that compensates for the height difference between black matrix and color filter. By providing this cushioning in advance, subsequent films are protected from the underlying surface irregularities, ensuring uniform thickness and quality throughout the display substrate
3Manufacturing precision
If rubbing is performed on an alignment layer over regions with height difference, then the alignment layer is applied, but non-uniform rubbing occurs resulting in poor display quality
Solution Approach 1:
The planarizing layer is formed before applying the alignment layer, creating a smooth surface that enables uniform rubbing during alignment. This preliminary smoothing eliminates the need for complex alignment procedures to accommodate surface irregularities, maintaining process simplicity while ensuring high display quality
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 planarizing layer effectively reduces the height difference, enhancing the surface smoothness of the display substrate, increasing product yield, and improving display quality by ensuring uniformity and smoothness critical for image display.
Implementation Method 1
exposing and developing the photoresist with a gray tone mask so as to form a fifth photoresist region corresponding to the color filter region and a sixth photoresist region corresponding to the black matrix region
Data Source
Figure 1~4
AI summary
Embodiments of the disclosure disclose a display substrate, a display device comprising the display substrate and a method for manufacturing the display substrate. The display substrate comprising a base substrate (1), a black matrix (2) and a color filter (3) formed on the base substrate (1), the color filter (3) and the black matrix (2) are arranged alternately with a height difference existing between the black matrix (2) and the color filter (3). The display substrate further comprises a planarizing layer (40) formed on the black matrix (2) or on both the black matrix (2)and the color filter (3). The planarizing layer (40) is configured to minimize the height difference between the black matrix (2) and the color filter (3). Thus, the height difference between the black matrix (2) and the color filter (3) can be minimized, and surface smoothness of the color filter (3) is improved effectively. Therefore, image displaying quality is improved.