Shadow Mask Slit Precision via Undercut Etching Control
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Solution Overview
Problem
Conventional shadow mask manufacturing methods face challenges in achieving precise and uniform slit sizes due to significant side etching, making it difficult to produce masks with fine pitches and patterns.
Innovation Solution
The method involves forming a metal pattern on a mask substrate, using it as an etching mask, and repeatedly filling undercut portions with photoresist to control side etching, allowing for the creation of shadow masks with precise slits and reduced side etching by forming undercut portions with a unit thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional wet etching method is used to manufacture shadow mask, then manufacturing process is simple, but side etching occurs significantly causing imprecise slit sizes
Solution Approach 1:
The patent divides the etching process into multiple sequential stages, each creating a specific portion of the slit structure. The first etching creates initial slits, the second etching creates undercut portions, and the third etching completes the penetration. This segmentation allows precise control over each etching step, eliminating the side etching problem that occurs in single-step conventional processes.
Solution Approach 2:
The patent applies preliminary protective coatings to the mask substrate before etching. A first protective coating is applied before the first etching process, and a second protective coating is applied before the second etching process. These preliminary protective actions prevent unwanted side etching and ensure precise slit dimensions are achieved.
2Manufacturing precision
If photoresist pattern is used as etching mask, then etching can be performed, but large amount of side etching occurs beneath the photoresist pattern
Solution Approach 1:
The patent introduces protective coatings as intermediary layers between the photoresist pattern and the mask substrate during etching. These protective coatings act as mediators that prevent the etching solution from causing side etching beneath the photoresist pattern, while still allowing the etching to proceed through the intended paths. This intermediary protection enables precise and uniform slit sizes to be achieved.
3Measurement precision
If pitch is reduced to achieve finer patterns, then resolution improves, but side etching becomes more severe making fine pitch manufacturing difficult
Solution Approach 1:
The patent segments the etching process into three distinct stages, each with specific protective coatings applied. This segmentation allows the manufacturing of fine pitch patterns by controlling each etching step independently, preventing the side etching that would otherwise make fine pitch manufacturing impossible.
Solution Approach 2:
The patent applies preliminary protective coatings before each etching stage. This preliminary protection is crucial for maintaining slit size control when manufacturing fine pitch patterns, as it prevents side etching from compromising the precise dimensions required for high resolution.
4Manufacturing precision
If multiple etching steps are performed to reduce side etching, then slit precision improves, but manufacturing time increases
Solution Approach 1:
The patent segments the etching process into three efficient sequential steps with protective coatings. While this requires multiple steps, each step is optimized to be relatively quick, and the segmentation enables parallel processing of different mask substrates during the process, reducing overall manufacturing cycle time while maintaining high slit size accuracy.
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
This approach enhances the precision and resolution of patterns by minimizing side etching and enabling the production of shadow masks with finer pitches and more accurate slit sizes.
Implementation Method 1
The mask substrate 10 is then wet etched using the photoresist pattern PR as an etching mask
Data Source
AI summary
Disclosed is a shadow mask having a fine slit that can improve precision and resolution of a pattern by reducing side etching during an etching process of a mask substrate, and a manufacturing method thereof. The shadow mask includes a mask substrate, a slit region formed by penetrating through the mask substrate, the slit region having a plurality of undercut portions at respective sides thereof, each undercut portion having a unit thickness, and a shadow region provided in the mask substrate, the shadow region corresponding to a region other than the slit region.