COA Substrate Opening Taper Angle Control
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Solution Overview
Problem
The existing COA substrate technology results in a large taper angle of the formed opening, leading to uneven coverage, high resistance, or disconnection during pixel electrode deposition, affecting the display effect.
Innovation Solution
A method of fabricating a COA substrate involving the formation of arc-shaped auxiliary through holes in the color resist layer and using a halftone mask for exposure and etching, which reduces the taper angle by etching a part of the color resist layer simultaneously with the second passivation layer, ensuring a continuous arc-shaped opening with increasing hole diameter from bottom to top.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the color resist layer is directly deposited on the first passivation layer and opened through exposure and development, then the manufacturing process is simple, but the taper angle of the opening becomes too large causing uneven coverage and high resistance
Solution Approach 1:
The patent divides the opening formation process into multiple stages: first forming an opening through the first passivation layer, then forming a second passivation layer, and finally forming the pixel electrode opening through the second passivation layer. This segmentation allows each layer to be etched with appropriate parameters, achieving a smaller overall taper angle while maintaining manufacturing feasibility
Solution Approach 2:
The patent introduces an additional dimensional layer (the second passivation layer) between the first passivation layer and the pixel electrode opening. This adds a vertical dimension to the structure, enabling better control over the opening taper angle by etching each layer separately with optimized parameters
2Productivity
If the opening has a large taper angle, then the etching process is faster, but the pixel electrode deposition shows uneven coverage and disconnection
Solution Approach 1:
The etching process is segmented into multiple steps, each targeting a specific passivation layer with optimized etching parameters. This allows each etching step to be performed at high speed while maintaining a small taper angle in each segment, resulting in an overall small taper angle that ensures proper pixel electrode connectivity
Solution Approach 2:
The patent changes the etching parameters for each passivation layer separately, optimizing the etching speed and taper angle for each layer. By adjusting parameters such as etching time, power, and gas flow for each layer, the process achieves both high productivity and reliable pixel electrode deposition
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 approach reduces the taper angle of the opening, preventing uneven coverage and disconnection during pixel electrode deposition, thereby improving the quality of the COA substrate.
Implementation Method 1
exposing the photoresist with a halftone mask
Implementation Method 2
the first passivation layer 108 and the second passivation layer 110 are etched
Data Source
AI summary
A color-filter on array (COA) substrate and a method of fabricating the same are described. A first through hole is disposed in a first passivation layer, a second through hole is disposed in the color resist layer, and a third through hole is disposed in the second passivation layer, wherein the first through hole communicates with the second through hole, and the second through hole communicates with the third through hole to collectively form an opening. A hole diameter of the opening gradually increases from bottom to top. A part of the color resist layer is etched while the second passivation layer is etched so as to reduce a taper angle of the opening. Therefore, a relatively large impedance value impedance or disconnection is avoided when depositing a pixel electrode.