Transflective LCD Array Substrate Mask Reduction
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Solution Overview
Problem
The high production cost of liquid crystal display (LCD) array substrates is largely attributed to the lithography process, which requires multiple photo-masks, necessitating a method to reduce the number of masks needed while maintaining display quality.
Innovation Solution
The method employs half-tone photo-masks and backward exposures to define metal and transparent conductive layers, reducing the number of photo-masks required to three to four, and optimizes storage capacitance design to increase capacitance value and aperture rate, thereby enhancing LCD brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional lithography process with multiple photo-masks is used, then manufacturing precision is maintained, but production cost increases and productivity decreases
Solution Approach 1:
The patent combines multiple lithography steps into a single exposure step by using a multi-layer photo-mask structure. The first photo-mask layer defines patterns for the first conductive layer, while the second photo-mask layer defines patterns for the second conductive layer, both exposed simultaneously to the same light source. This merging of steps reduces the total number of photo-masks needed and decreases manufacturing complexity, directly addressing the contradiction between ease of manufacture and productivity.
Solution Approach 2:
The patent creates a universal photo-mask system where a single exposure process serves multiple patterning functions. The multi-layer photo-mask structure allows one exposure step to define patterns for multiple conductive layers that would traditionally require separate exposure steps. This multi-functionality reduces the number of sequential operations needed, thereby increasing production volume while maintaining manufacturing precision.
2Productivity
If number of photo-masks is reduced to three to four, then production cost decreases and productivity increases, but manufacturing process complexity increases
Solution Approach 1:
The patent segments the photo-mask into multiple functional layers, where each layer is responsible for defining patterns of specific conductive layers. The first photo-mask layer handles patterning for the first conductive layer, while the second photo-mask layer handles patterning for the second conductive layer. This segmentation allows the complex patterning task to be divided into manageable components that can be processed simultaneously, reducing the total number of exposure steps while maintaining the ability to create precise patterns for multiple layers.
3Quantity of substance
If storage capacitance occupies more substrate area, then capacitance value increases, but aperture rate decreases and brightness is reduced
Solution Approach 1:
The patent utilizes the third dimension (vertical stacking) to increase capacitance value without occupying more horizontal substrate area. By forming storage capacitance structures that extend vertically through multiple conductive layers and dielectric layers, the patent achieves higher capacitance density. This dimensional transition allows the aperture area to remain large for brightness while the capacitance value is enhanced through vertical structure development, effectively resolving the contradiction between capacitance quantity and illumination intensity.
Data Source
AI summary
A method of manufacturing an array substrate of a transflective liquid crystal display is provided. Utilizing backward exposure and half-tone photo-mask to reduce the number of photo-masks used in the manufacturing process, only three to four photo-masks are used to manufacture a transflective liquid crystal display.