LCD Align Marks for Substrate Registration
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Solution Overview
Problem
The existing liquid crystal display fabrication methods face productivity and yield issues due to misalignment between substrates, which can lead to light leakage defects and require additional photolithography processes, degrading the aperture ratio and increasing costs.
Innovation Solution
The proposed solution involves forming align marks on both substrates using the same material as the alignment films, with shapes like circles, squares, or crosses, and sizes ranging from 600 μm to 1200 μm, allowing for improved alignment accuracy and reducing the number of photolithography processes by forming the upper align mark during the upper alignment film process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the width of the black matrix is increased to prevent misalignment defects, then light leakage defects are reduced, but the aperture ratio is degraded
Solution Approach 1:
The patent introduces align marks as intermediary reference features that mediate the alignment process between substrates. These marks provide precise positioning references that enable accurate substrate alignment without requiring excessive black matrix width, thus resolving the contradiction between alignment accuracy and aperture ratio
Solution Approach 2:
The align marks are formed in advance during the black matrix formation process, establishing precise alignment references before substrate bonding occurs. This preliminary positioning action enables accurate alignment without needing to increase black matrix dimensions, thereby maintaining high aperture ratio while ensuring reliable alignment
2Manufacturing precision
If additional photolithography processes are used to form align marks, then alignment accuracy is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges the align mark formation process with the black matrix photolithography process. By forming both the black matrix and align marks in the same photolithography step using a single photoresist layer, the invention eliminates additional photolithography processes while maintaining high alignment accuracy, thus resolving the contradiction between manufacturing precision and process complexity
3Adaptability or versatility
If separate processes are used to form align marks and black matrix, then flexibility is improved, but productivity is reduced
Solution Approach 1:
The invention combines align mark formation and black matrix formation into a single integrated photolithography process. This merging of operations reduces the total number of fabrication steps, eliminates intermediate processing stages, and enables simultaneous formation of both features, thereby significantly improving productivity while maintaining process flexibility through unified pattern control
Data Source
AI summary
A liquid crystal display (LCD) device includes first and second substrates with a liquid crystal material therebetween; a first alignment film formed on the first substrate and a second alignment film formed on the second substrate; a first align mark on the first substrate, the first align mark formed of the same material as the first alignment film and formed in a shape of any one of a circle, square and cross; and a second align mark to be aligned with the first align mark on the second substrate.