Electrostatic Mask Chucking Structure for OLED Deposition Alignment
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Solution Overview
Problem
In the manufacture of OLED display devices, metallic shadow masks used in PECVD and ALD processes often become misaligned or mispositioned, leading to shadowing effects and 'mura' or 'clouding' issues due to insufficient contact with the substrate, which affects the quality of the encapsulation layers.
Innovation Solution
The use of an electrostatic chuck and compressible buttons in a substrate support system ensures precise alignment and secure contact of the mask with the substrate, preventing shadowing effects by forming an electrical circuit and maintaining contact through the electrostatic chuck and compressible buttons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a metallic shadow mask is used in PECVD/ALD processes, then the mask provides effective shielding and control of deposition, but the mask becomes misaligned and mispositioned relative to the substrate due to insufficient contact
Solution Approach 1:
The patent replaces the traditional mechanical contact system (relying solely on gravitational force and physical weight) with an electrostatic field-based system. The electrostatic chuck generates an electrostatic field that acts on the conductive mask frame, providing stable positioning and alignment without requiring direct mechanical contact between the mask and substrate support. This substitution resolves the contradiction by maintaining precision while improving contact stability through field-based interaction.
Solution Approach 2:
The patent changes the physical state and interaction parameters of the mask support system by introducing electrostatic forces. By applying voltage to the electrostatic chuck, the interaction between the mask and substrate support transitions from purely mechanical to electro-mechanical, enabling dynamic control of mask positioning and contact pressure. This parameter change allows the system to maintain both high alignment precision and stable contact throughout the deposition process.
2Reliability
If the mask is misaligned or mispositioned, then the mask cannot be properly secured to the substrate, but improving contact may require complex mechanical structures
Solution Approach 1:
The patent simplifies the substrate support structure by replacing complex mechanical adjustment mechanisms with an electrostatic field-based positioning system. The electrostatic chuck provides automatic alignment and contact stabilization through electrostatic forces, eliminating the need for complex mechanical clamps, springs, or adjustment devices. This substitution reduces structural complexity while improving contact reliability.
Solution Approach 2:
The electrostatic chuck acts as an intermediary between the substrate support and the mask. Instead of directly mechanically coupling the mask to the substrate support, the electrostatic field serves as a mediator that transmits positioning and contact forces. This intermediary approach simplifies the direct mechanical interface while maintaining reliable contact and alignment.
3Manufacturing precision
If the mask is not in proximity to the substrate, then shadowing effects and errant coating occur, but maintaining close proximity requires precise positioning mechanisms
Solution Approach 1:
The patent replaces complex mechanical positioning mechanisms with an electrostatic field-based positioning system. The electrostatic chuck generates forces that automatically pull the conductive mask frame into close proximity with the substrate and maintain it there throughout the deposition process. This substitution achieves precise proximity control without requiring mechanical adjustment devices, reducing the overall system complexity.
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 solution enhances the alignment and contact between the mask and substrate, minimizing shadowing and 'mura' effects, thereby improving the yield and enabling narrow or zero bezel around OLED displays by ensuring consistent and precise deposition of encapsulation layers.
Implementation Method 1
electrostatic chuck disposed below the substrate receiving surface
Implementation Method 2
a plurality of compressible buttons disposed within a respective opening formed in the recessed portion
Data Source
AI summary
Embodiments of the disclosure include methods and apparatus for electrostatically coupling a mask to a substrate support in a deposition chamber. In one embodiment, a substrate support is disclosed that includes a substrate receiving surface, a recessed portion disposed about a periphery of the substrate receiving surface, an electrostatic chuck disposed below the substrate receiving surface, and a plurality of compressible buttons disposed within a respective opening formed in the recessed portion that form an electrical circuit with the electrostatic chuck.