Electrostatic Deposition Mask Structure for High-PPI Alignment
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Solution Overview
Problem
High-resolution deposition masks used in manufacturing high-resolution display panels for wearable devices like HMDs and AR glasses suffer from warpage and deformation due to residual stress, leading to misalignment between organic light-emitting layers and anode electrodes during the deposition process.
Innovation Solution
A deposition mask with a mask frame and membrane design featuring recesses and electrodes to enhance contact with the substrate, utilizing electrostatic forces for precise alignment, including a grid region with a first recess and a rib region with a lower electrode, and a dielectric pattern to improve adherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a high-resolution deposition mask is manufactured by forming a membrane with pixel openings and partially etching the substrate to form cell openings, then the resolution can be increased to approximately 3000 PPI or higher, but warpage or deformation occurs due to residual stress inside the membrane and difference in thermal expansion rate between the substrate and the membrane
Solution Approach 1:
The deposition mask is divided into a mask frame and a separate membrane, allowing independent optimization of each component. The membrane can be formed without the substrate etching step that causes warpage, while the mask frame provides structural support and defines the cell openings.
Solution Approach 2:
The membrane acts as an intermediary layer between the mask frame and the substrate. It transfers the pattern from the mask frame to the substrate while maintaining its own structural integrity and reducing the impact of residual stress and thermal expansion differences.
2Manufacturing precision
If the deposition mask is manufactured with the above structure, then the resolution can be increased to approximately 3000 PPI or higher, but the deposition mask cannot be brought into sufficiently close contact with the backplane substrate, so misalignment occurs between the organic light-emitting layers and anode electrodes
Solution Approach 1:
Separating the mask frame from the membrane allows the membrane to be optimized for close contact with the substrate while the mask frame maintains the high-resolution pattern. This segmentation enables independent optimization of contact quality and pattern precision.
Solution Approach 2:
The membrane thickness and elasticity parameters can be independently optimized to ensure close contact with the substrate during deposition, while the mask frame maintains the high-resolution pattern definition. This parameter optimization resolves the conflict between contact quality and alignment precision.
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 enhanced contact and alignment ensure accurate deposition of organic light-emitting layers, reducing misalignment issues and improving the manufacturing quality of high-resolution display panels.
Implementation Method 1
utilizing electrostatic forces for precise alignment
Data Source
AI summary
A deposition mask includes a mask frame defining cell openings therein, and a membrane including mask cell regions disposed above and overlapping the cell openings, respectively, and a grid region disposed between the mask cell regions. A recess is defined at a surface portion of the membrane, and the mask frame includes a rib region defining the cell openings and a lower electrode disposed to be spaced apart from the recess in a thickness direction of the mask frame.