Color Filter Sidewall Profile Control via Two-Stage Exposure
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Solution Overview
Problem
As pixel sizes decrease, achieving positional accuracy and minimizing taper profiles in color filters becomes challenging due to bottom reflected light during the exposure process in photolithography, affecting the quality of color filters in flat panel displays.
Innovation Solution
A two-stage exposure process using lights of different wavelengths, where a first exposure with deep ultraviolet light is followed by a second exposure with ultraviolet light, reduces bottom reflection and results in color filters with substantially vertical sidewalls and a slant jut, enhancing resolution and reducing taper profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography is used to produce color filters with decreasing pixel sizes, then high resolution is achieved, but positional accuracy deteriorates due to bottom reflected light
Solution Approach 1:
The exposure process is segmented into two distinct stages: first exposure and second exposure. This segmentation allows each exposure to be optimized for different purposes - the first exposure creates the base pattern while the second exposure corrects positional accuracy and reduces taper profiles caused by bottom reflected light.
Solution Approach 2:
The first exposure is performed as a preliminary action to establish the base color filter pattern. This preliminary exposure creates an initial structure that is then refined by the second exposure, allowing the harmful bottom reflected light effects to be minimized in the final pattern formation.
2Ease of manufacture
If conventional single-stage exposure is used, then manufacturing process is simple, but taper profiles are formed at the lower portions of color filters
Solution Approach 1:
The manufacturing process is segmented into two exposure stages with different exposure conditions. The first exposure uses one set of parameters to create the base pattern, while the second exposure uses different parameters to correct the sidewall profile and eliminate taper effects, achieving vertical sidewalls without excessive process complexity.
Solution Approach 2:
Exposure parameters are changed between the two stages - the first exposure and second exposure use different exposure doses and potentially different light sources or wavelengths. This parameter change allows the formation of vertical sidewalls by controlling the polymerization depth and profile development.
3Manufacturing precision
If pixel size is decreased to improve resolution, then more pixels fit in the display, but achieving positional accuracy becomes more challenging
Solution Approach 1:
The patterning process is divided into two exposures that work together to achieve high resolution and positional accuracy simultaneously. The segmentation allows the first exposure to define the fine features while the second exposure ensures precise positioning, enabling both high pixel density and accurate placement.
Solution Approach 2:
The two-stage exposure process provides a form of feedback control where the first exposure creates a pattern that is then refined by the second exposure. This iterative approach allows correction of positioning errors and optimization of the final pattern accuracy for small pixel sizes.
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
The two-stage exposure process improves the resolution and accuracy of color filter patterns by minimizing bottom reflection and maintaining upright sidewalls, allowing for precise formation of green, blue, and red color filters with improved positional accuracy and reduced taper profiles.
Implementation Method 1
performing a first exposure process with a first light at a first wavelength to expose a portion of the green color filter layer
Implementation Method 2
performing a second exposure process with a second light at a second wavelength to the exposed portion of the green color filter layer
Data Source
AI summary
A color filter pattern including a plurality of color filters arranged in a pattern and the manufacturing method thereof are provided. By performing at least one two-stage exposure process to a color filter layer, the plurality of color filters are formed with a sharp profile.