Substrate Alignment Using Position Marks for Hidden Reference Detection
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Solution Overview
Problem
Existing alignment systems face challenges in precisely aligning substrates due to the need for precise positioning of substrate holders, which is difficult to achieve with current methods, especially when alignment marks are inaccessible or obscured, leading to potential contamination and misalignment during measurement.
Innovation Solution
The use of position marks, such as QR codes, to determine the precise alignment of substrates by correlating alignment marks with position marks, allowing for precise alignment without direct observation of alignment marks, even when they are concealed, and reducing the need for large-scale substrate movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a measuring device is inserted between substrates to measure alignment marks, then alignment measurement can be performed, but the measuring device contaminates the substrate surface and requires large separation distance
Solution Approach 1:
The patent introduces position marks as an intermediary reference system. Instead of directly measuring alignment marks through a physical measuring device that contacts substrates, the system uses position marks detected by positioning optics to calculate substrate positions indirectly. This mediator approach eliminates the need for physical insertion between substrates, preventing contamination while maintaining measurement capability.
Solution Approach 2:
The patent replaces the mechanical measuring device insertion approach with an optical detection system. Positioning optics detect position marks and alignment optics detect alignment marks, with positions calculated through coordinate transformations. This substitution eliminates mechanical contact between measuring devices and substrates, preventing contamination and enabling measurement at minimal separation distances.
2Measurement precision
If substrates are separated by a large distance to accommodate measuring device insertion, then measurement can be performed, but lateral shift between substrates occurs during approach, destroying alignment
Solution Approach 1:
The patent performs preliminary detection of position marks and alignment marks when substrates are in a known reference position. The system pre-calculates the relationship between position marks and alignment marks, storing this correlation data. During subsequent alignment operations, this pre-established reference relationship enables precise alignment without requiring large substrate movements, preventing lateral shifts that would destroy alignment.
3Ease of operation
If substrate holders are used for positioning substrates, then substrates can be held and moved, but precise positioning in micrometer or nanometer range is difficult to achieve due to large travel distances
Solution Approach 1:
The patent introduces position marks as an intermediary reference system attached to or associated with substrate holders. These position marks serve as mediators between the substrate holder positioning system and the alignment requirement. By detecting position marks with positioning optics and calculating substrate positions based on these marks rather than directly measuring alignment marks, the system achieves precise positioning without requiring the substrate holder positioning system itself to have micrometer or nanometer-level precision.
Solution Approach 2:
The patent replaces direct mechanical positioning measurement with an optical detection and calculation system. Instead of relying on the mechanical positioning precision of substrate holders, the system uses positioning optics to detect position marks and calculates actual substrate positions through coordinate transformations. This substitution transforms a mechanical precision problem into an optical measurement and computational problem, achieving higher precision independent of mechanical travel distances.
4Measurement precision
If conventional alignment systems are used, then alignment marks can be measured, but expensive and maintenance-intensive interferometers are required for precise position measurement
Solution Approach 1:
The patent creates a virtual reference system using position marks that copy the physical reference framework. Instead of using expensive interferometers to directly measure substrate positions, the system uses simpler positioning optics to detect position marks, which serve as optical copies or representations of the reference coordinate system. The actual position calculations are performed through coordinate transformations of these mark positions, replacing complex interferometric measurement with simpler optical detection and computation.
Solution Approach 2:
The patent replaces expensive, maintenance-intensive interferometers with simpler, cheaper positioning optics and position mark detection systems. The position marks themselves are simple graphical or geometric features that can be manufactured inexpensively on substrates or substrate holders. This substitution dramatically reduces system cost and maintenance requirements while maintaining measurement precision through computational methods rather than expensive hardware.
Data Source
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AI summary
The invention relates to a device and to a method for aligning substrates.