LCD Column Spacer Step-Difference Compensation
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Solution Overview
Problem
The existing process for forming black column spacers in liquid crystal display (LCD) devices faces challenges in accurately imparting a step difference between the main column spacer and the sub-column spacer due to process spread, which affects the manufacturing efficiency and quality of the display device.
Innovation Solution
The implementation of a step-difference compensation portion above the thin film transistors, combined with a main column spacer and a sub-column spacer that overlap this compensation portion, allows for the effective formation of a black matrix structure using a single mask with the same light transmittance, thereby simplifying the manufacturing process and reducing the risk of misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single mask is used to form the main column spacer, sub-column spacer, and black matrix with different thicknesses, then the manufacturing process is simplified, but the step difference between the sub-column spacer and black matrix cannot be effectively imparted due to process spread
Solution Approach 1:
The patent introduces a step difference compensation portion formed before the black matrix and column spacers. This compensation portion pre-establishes a height difference that compensates for the process spread occurring during subsequent photolithography steps, enabling precise step difference control between the sub-column spacer and black matrix even when using a single mask
2Manufacturing precision
If multiple masks with different transmittances are used to form structures with different thicknesses, then the step difference can be precisely controlled, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the formation of the black matrix and column spacers into a single photolithography step using one mask. The step difference compensation portion enables this merging by pre-establishing the necessary height differences, eliminating the need for multiple masks with different transmittances and their associated alignment complexities
Data Source
AI summary
A display device includes: a base substrate, on which first and second light blocking areas extending in first and second directions, respectively, and a pixel area are defined; a gate line above the base substrate in the first light blocking area; a data line above the base substrate in the second light blocking area; thin film transistors connected to the gate and data lines; a color filters above the base substrate in the pixel area, where the color filters have an island shape; a step-difference compensation portion above thin film transistors; a pixel electrode above the color filter in the pixel area; a black matrix above the step-difference compensation portion in the first light blocking area; and main and sub column spacers protruding from the black matrix and spaced apart from each other. The main column spacer overlaps the step-difference compensation portion.