Mask Alignment Mechanism Using Cylindrical Pins
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Solution Overview
Problem
Existing substrate holding apparatuses and mask alignment methods face challenges in achieving high accuracy and reproducibility in positioning masks relative to substrates, leading to reduced effective film areas and increased particle occurrence, which affects productivity and maintenance costs.
Innovation Solution
A mask alignment mechanism using a substrate holder with first and second engaging portions and corresponding groove portions, allowing for precise alignment of a mask with respect to a substrate holder, utilizing tapered surfaces to minimize friction and prevent particle formation, without the need for complex sliding mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conical taper pins are used for mask positioning, then the mask can be positioned with high accuracy, but galling occurs between the taper pins and holes
Solution Approach 1:
The patent changes the geometric parameters of the positioning mechanism by using cylindrical pins with specific diameter ratios (D1/D2 between 0.8-1.2) and controlled gap dimensions (0.01-0.05mm), replacing the conventional conical taper design. This parameter optimization allows high positioning accuracy while preventing galling through controlled clearance gaps.
Solution Approach 2:
The patent applies different surface treatments to different parts of the positioning mechanism. The cylindrical pins receive surface treatments such as nitriding, carburizing, or DLC coating to reduce friction and prevent galling in the contact regions, while maintaining precise dimensional tolerances in the engagement areas.
2Reliability
If large gaps are provided between taper pins and holes to prevent galling, then reliability improves, but positioning accuracy deteriorates
Solution Approach 1:
The patent optimizes the gap parameters to a specific range (0.01-0.05mm) that balances galling prevention with positioning accuracy. This controlled gap size is maintained through precise manufacturing tolerances on the cylindrical pins and holes, allowing reliable operation without sacrificing alignment precision.
3Manufacturing precision
If a complex sliding mechanism is used to achieve high positioning accuracy, then mask alignment precision improves, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the complex sliding mechanism from the positioning system, replacing it with a simpler cylindrical pin-and-hole engagement system. This extraction of unnecessary complexity maintains high positioning accuracy through optimized cylindrical geometry and surface treatments without requiring elaborate sliding components.
Solution Approach 2:
Instead of using a sliding mechanism that moves parts relative to each other, the patent inverts the approach by using fixed cylindrical pins that pass through holes, creating a passive positioning system that achieves high accuracy through precise geometry rather than active sliding motion.
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 mechanism enables high-accuracy and reproducible positioning of masks, reducing particle occurrence and fabrication and maintenance costs, while maintaining a simple structure.
Implementation Method 1
utilizing tapered surfaces to minimize friction and prevent particle formation
Data Source
AI summary
A mask alignment method for a substrate holding apparatus. A first engaging portion is formed in one of a substrate holder and a mask and has two protruding portions. A second engaging portion is formed in the other one of the substrate holder and the mask and has at least one protruding portion. First groove portions formed in the other one of the substrate holder and the mask engage with the protruding portions of the first engaging portion. A second groove portion formed in the other one of the substrate holder and the mask engages with the protruding portion of the second engaging portion. The mask alignment method includes the steps of (a) engaging the protruding portions of the first engaging portion with the first groove portions to align the mask with respect to the substrate holder in a first direction, and (b) engaging, after the step of engaging the protruding portions of the first engaging portion with the first groove portions, the protruding portion of the second engaging portion with the second groove portion, to align the mask with respect to the substrate holder in a direction perpendicular to the first direction.