Nano-imprint Alignment Using Optical Grating Sensors
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Solution Overview
Problem
Current nano-fabrication techniques face challenges in accurately aligning molds and templates during imprint lithography, particularly in determining the relative position of the template active area and substrate edge, and compensating for centering errors in the imprinting process, which affects the precision of feature formation on substrates.
Innovation Solution
A system utilizing a scanning sensor system with gratings of specific pitch around the active area to generate and receive optical energy, allowing for precise positioning of the template and substrate, and using the same sensor system to detect both the template and substrate edges, enabling accurate alignment and compensation for orientation errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional alignment methods are used in imprint lithography, then the process can be completed, but the alignment precision between template and substrate is insufficient
Solution Approach 1:
The patent applies preliminary action by detecting alignment marks and grating patterns on both the template and substrate before the actual imprinting process. The system measures the relative positions and orientations of these features in advance, allowing for precise compensation of centering errors before the imprinting occurs, thereby achieving high alignment precision without requiring complex real-time adjustments during fabrication.
Solution Approach 2:
The patent replaces conventional mechanical alignment methods with an optical detection system. Instead of relying on mechanical stage positioning alone, the system uses optical sensors to detect grating patterns and alignment marks, measures their positions and orientations, and calculates the relative geometry between template and substrate. This optical measurement approach provides higher precision and enables better compensation for centering errors.
2Measurement precision
If the template and substrate are positioned without precise optical detection, then the setup is simpler, but the relative position determination is inaccurate
Solution Approach 1:
The patent applies universality by designing a multi-functional optical detection system that serves multiple purposes: detecting alignment marks on the template, detecting grating patterns on both template and substrate, measuring relative positions, and determining orientations. This single integrated optical system replaces what would otherwise require multiple separate measurement devices, achieving high measurement precision while controlling overall system complexity.
Solution Approach 2:
The patent uses grating patterns as an intermediary reference element. These gratings are formed on both the template and substrate and serve as a common reference for optical measurement. By measuring the relative positions and orientations of the gratings using optical detection, the system can accurately determine the relative geometry between template and substrate without requiring direct mechanical measurement between the two components.
3Manufacturing precision
If centering errors are not compensated, then the alignment process is faster, but the feature formation precision deteriorates
Solution Approach 1:
The patent applies feedback by measuring the actual relative positions and orientations of the template and substrate using optical detection of grating patterns and alignment marks. The system calculates the centering errors from these measurements and uses this information to adjust the positioning before imprinting. This feedback-based compensation ensures high feature formation precision while maintaining efficient alignment process time.
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 system achieves precise alignment and orientation of the template and substrate, improving the accuracy of feature formation on substrates to within a few microns, facilitating high-yield production of integrated circuits and other nano-structured components.
Implementation Method 1
a scanning sensor system that generates a beam of optical energy and is configured to receive only portions of the optical energy reflected from detection surfaces
Data Source
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Figure 3A~3C
Figure 4A~4B
AI summary
A transparent imprint template mold is configured with gratings surrounding the active imprint area. The gratings are fabricated at the same time as the active area and thus accurately define the active area with respect to the gratings. The substrate is positioned in tool coordinates under the template mold. A sensor system generates a beam of optical energy and receives reflected energy only at a specific angular window and is used to locate the template mold. The sensor system is scanned to locate the substrate and the gratings in tool coordinates. In this manner, the relative position of the template mold is determined with respect to the substrate in tool coordinates. The substrate is then accurately positioned with respect to the template mold. The system may be used to track imprinted pattern position relative to the substrate and to determine concentricity of patterns to substrates.