Staggered Deposition Mask Geometry to Reduce Shadow Defects
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Solution Overview
Problem
In the manufacturing of organic EL display devices, the deposition material tends to adhere to the wall surfaces of the deposition mask instead of passing through the holes, leading to a phenomenon known as 'shadow' which results in reduced thickness of the deposited layer and defects.
Innovation Solution
A deposition mask with through holes arranged in a staggered pattern and flat regions between adjacent holes, where the dimensions of the flat regions increase away from the center line, reducing the occurrence of shadow and defects by guiding the deposition material effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the deposition mask has through holes for material passage, then the deposited layer can be formed on the substrate, but the deposited material adheres to the wall surfaces of the through holes causing shadow and reduced layer thickness
Solution Approach 1:
The patent introduces a flat region between adjacent through holes that extends in the thickness direction of the mask, creating a three-dimensional structure. This flat region serves as an additional dimension that guides the deposited material away from the wall surfaces and toward the center of the through holes, preventing shadow effects and ensuring uniform layer thickness.
Solution Approach 2:
The flat region acts as an intermediary structure between the through holes, providing a surface that redirects the deposited material. This intermediate structure prevents direct adhesion of material to the wall surfaces by guiding it along the flat region toward the hole centers, thereby eliminating the shadow problem.
2Shape
If the through holes are arranged in a staggered pattern, then the mask structure is optimized, but the flat region dimensions must be carefully controlled to avoid material adhesion issues
Solution Approach 1:
The patent applies different dimensional characteristics to different regions of the mask. The flat region has specific dimension requirements (first dimension between 0.01-0.5 times the through hole pitch, second dimension between 0.1-2.0 times the mask thickness) that are optimized for its specific function of guiding material, while the through holes maintain their staggered arrangement pattern. This local optimization ensures both structural integrity and material guidance functionality.
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 reduces the occurrence of shadow and defects in the deposited layer, ensuring consistent thickness and improving the manufacturing process efficiency by effectively guiding the deposition material through the mask.
Implementation Method 1
a deposited material containing an organic material is made to adhere to the substrate via the through holes of the deposition mask
Data Source
AI summary
A deposition mask includes a metal plate including first and second surfaces located opposite each other, through holes bored through the metal plate from the first surface to the second surface, and a flat region located between two through holes adjacent to each other in a case where the deposition mask is seen from the second surface side. The through holes are arrayed in a staggered arrangement in first and second directions in planar view. The flat region includes first and second flat regions located at first and second sides, respectively, of a first center line. The first center line passes through center points of two through holes adjacent to each other in the first direction. The first and second flat regions include portions in which dimensions of the first and second flat regions in the first direction increase away from the first center line, respectively.