Invar Metal Mask Substrate Surface Roughness Control
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Solution Overview
Problem
Vapor deposition metal masks used in organic EL display manufacturing face challenges in achieving structural accuracy due to light scattering during the resist mask formation process, leading to discrepancies between the designed and actual resist mask structures, which affects the precision of openings formed by wet etching.
Innovation Solution
A vapor deposition metal mask substrate with a nickel-containing metal sheet, specifically an invar sheet, is developed, featuring a surface roughness of less than or equal to 0.019 μm and specular reflectance between 53.0% and 97.0%, which limits light scattering and enhances the accuracy of resist mask formation, thereby improving the structural accuracy of the openings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional metal mask substrate is used, then the manufacturing process is simple, but light scattering during resist mask formation causes discrepancies between designed and actual resist mask structures
Solution Approach 1:
The patent applies parameter changes by precisely controlling the surface roughness parameters (Sa ≤ 0.019 μm, Sz ≤ 0.308 μm) and specular reflectance (53.0% ≤ R ≤ 97.0%) of the metal mask substrate. These parameter specifications directly reduce light scattering during photolithography, thereby improving the structural accuracy of the openings without fundamentally changing the manufacturing process complexity
Solution Approach 2:
The patent implements preliminary action by pre-controlling the surface properties of the metal mask substrate before the resist mask formation process. By establishing the required surface roughness and reflectance characteristics in advance, the patent prevents light scattering issues before they occur during photolithography, ensuring accurate pattern transfer
2Illumination intensity
If the surface roughness is reduced to improve light reflectance, then light scattering decreases, but the surface preparation process becomes more complex
Solution Approach 1:
The patent uses parameter changes by defining specific ranges for surface roughness (Sa, Sz) and specular reflectance (R). These parameter specifications enable optimization of light reflectance while maintaining manufacturability, as the parameters can be controlled through standard surface treatment processes without requiring extreme or complex preparations
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 solution significantly reduces the difference between the designed and actual resist mask structures, enhancing the precision of the openings in the vapor deposition metal mask, and minimizes thermal expansion issues due to the invar material's low thermal expansion coefficient, ensuring consistent performance across two-dimensional directions.
Implementation Method 1
At least part of the light incident on the resist layer scatters on the surface of the vapor deposition metal mask substrate
Implementation Method 2
a specular reflectance of incident light to the target surface is between 53.0% and 97.0%, inclusive
Implementation Method 3
the invar material's low thermal expansion coefficient, ensuring consistent performance across two-dimensional directions
Data Source
AI summary
A vapor deposition metal mask substrate includes a nickel-containing metal sheet including a obverse surface and a reverse surface, which is opposite to the obverse surface. At least one of the obverse surface and the reverse surface is a target surface for placing a resist layer. The target surface has a surface roughness Sa of less than or equal to 0.019 μm. The target surface has a surface roughness Sz of less than or equal to 0.308 μm.