Active Alignment Shadow Mask Micro-Display Deposition
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Solution Overview
Problem
The alignment of high-resolution shadow masks with micro-display substrates during deposition processes is challenging due to thermal drift and the need for continuous contact, which complicates the alignment process and can lead to misalignment issues, especially for subpixel dimensions below 3.5 microns.
Innovation Solution
An active alignment method that involves performing initial and subsequent alignment processes by moving the shadow mask or substrate vertically to achieve precise alignment, capturing alignment images, and adjusting positions to maintain contact during deposition, allowing for continuous alignment inspection and correction to prevent misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the substrate and shadow mask are kept in full contact during deposition, then feathering effect is avoided and deposition precision is improved, but alignment inspection and correction become difficult due to inability to move components
Solution Approach 1:
The system dynamically adjusts the contact state between substrate and shadow mask. During alignment inspection, the components are separated to allow relative movement and optical access. During deposition, they are brought into full contact to prevent feathering. This dynamic transition resolves the contradiction between maintaining contact for precision and separating for inspection.
Solution Approach 2:
The alignment inspection and contact maintenance occur in periodic cycles during the deposition process. The system periodically separates the mask and substrate for alignment verification, then returns them to contact position for continued deposition. This periodic alternation allows both alignment inspection and deposition precision to be maintained throughout the process.
2Measurement precision
If the shadow mask and substrate are separated for alignment adjustment, then alignment accuracy can be improved, but thermal drift increases and contact stability deteriorates
Solution Approach 1:
Alignment adjustments are performed preliminarily before the deposition process begins, and periodically at predetermined intervals during deposition. By performing alignment actions at these specific times rather than continuously, the system minimizes the duration of separation, thereby reducing thermal drift accumulation while still maintaining alignment accuracy when needed.
Solution Approach 2:
The system uses optical feedback to detect alignment status and automatically triggers separation-only when misalignment beyond a threshold is detected. This feedback-controlled approach ensures separation occurs only when necessary, minimizing disruption to thermal stability and contact integrity while maintaining alignment accuracy when needed.
3Measurement precision
If frequent alignment inspections are performed, then alignment accuracy is maintained, but process time increases and productivity decreases
Solution Approach 1:
Instead of performing full alignment inspection cycles continuously, the system performs partial inspections at predetermined intervals during deposition. The inspection frequency is optimized to detect significant drift events without unnecessarily interrupting the deposition process, thus maintaining alignment accuracy while preserving deposition efficiency and productivity.
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 method ensures accurate and continuous alignment of shadow masks with substrates during material deposition, reducing the risk of thermal drift-induced misalignment and maintaining the required precision for high-resolution micro-displays.
Implementation Method 1
generating a material deposition flow to be deposited onto a surface of the substrate through shadow mask patterning holes
Implementation Method 2
During the organic material deposition, which is a thermal process, the kinetic energy of molecules arriving at the surface of the substrate may affect thermal conditions of the system
Implementation Method 3
the kinetic energy of molecules arriving at the surface of the substrate may affect thermal conditions of the system and result in slight drift of the substrate against the shadow mask
Data Source
AI summary
A method of active alignment of a shadow mask to a substrate includes a first alignment by moving the shadow mask and the substrate a first distance in a vertical direction, capturing a first alignment image, determining at least one of a first correction distance and a first rotational correction angle, and aligning the shadow mask and the substrate by moving the first correction distance and rotating the first rotational correction angle. The method further includes performing a first material deposition process on the substrate and continuously capturing a first series of alignment images during the generation of the first material deposition flow. During the generation of the first material deposition flow the first series of alignment images are analyzed to determine a second correction distance and a second rotational correction angle and determining whether second distance and/or rotational correction angle is greater than or equal to a predetermined value to cause a second alignment process to occur.