Photo Mask Triangular Wing Patterns for IPS LCD Aperture Ratio
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Solution Overview
Problem
The aperture ratio of in-plane-switching (IPS) mode liquid crystal display (LCD) devices is limited by the minimum width of pixel and common electrodes, which is constrained by the exposure resolution in photolithography processes, resulting in reduced viewing angle and brightness due to non-uniform liquid crystal molecule driving and limited effective opening regions.
Innovation Solution
A photo mask with a mask pattern featuring unit mask patterns in a single line, including a body portion and triangular wing portions, is used to form fine patterns, allowing for the reduction of electrode line widths below the exposure resolution limit, enhancing the aperture ratio and brightness of IPS mode LCD devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography is used to form pixel and common electrodes, then the manufacturing process is simple and reliable, but the electrode line width cannot be reduced below the exposure resolution limit, resulting in limited aperture ratio
Solution Approach 1:
The mask pattern is divided into multiple unit mask patterns arranged in a single line, where each unit mask pattern includes a body portion and wing portions. This segmentation allows the formation of fine electrode patterns with line widths below the exposure resolution limit by using the interference effects between adjacent unit patterns, thereby resolving the contradiction between manufacturing precision and device complexity.
2Area of stationary object
If electrode line width is reduced to increase aperture ratio, then the effective opening region increases and viewing angle improves, but the manufacturing precision requirements exceed conventional photolithography capabilities
Solution Approach 1:
The invention changes the geometric parameters of the mask pattern, specifically using unit mask patterns with body portions and triangular wing portions where the body portion length is 2-3 times the wing portion height, and the wing portion apex angle is 60-90 degrees. This parameter optimization enables the formation of electrodes with line widths of 1.5-2.0 μm, achieving high aperture ratio while remaining within manufacturable precision ranges.
3Illumination intensity
If the number of effective opening regions is increased to improve brightness and viewing angle, then the aperture ratio increases, but the electrode finger width must be reduced below conventional exposure resolution limits
Solution Approach 1:
The invention introduces a new dimensional approach by using three-dimensional mask pattern structures with specific height and angle relationships. The unit mask patterns have body portions with lengths 2-3 times the wing portion height, creating optical interference effects that enable sub-resolution patterning. This dimensional transformation allows electrode finger widths of 1.5-2.0 μm to be formed, increasing the number of effective opening regions and improving brightness without requiring impossible manufacturing precision.
Data Source
AI summary
The photo mask includes a mask substrate, and a mask pattern formed to include a plurality of unit mask patterns which are arranged in a single line for a fine pattern formation. The unit mask pattern is configured to include a body portion positioned at a center and wing portions formed in a triangular shape at both sides of the body portion.