Lithographic Apparatus Vibration Filter Design
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Solution Overview
Problem
Vibrations in lithographic apparatuses negatively impact reproducibility and measurement accuracy during the manufacturing process, as direct measurement of vibrations by one sensor may not accurately represent the vibrations experienced by other components or parameters of interest.
Innovation Solution
Implementing a method that uses first and second sensors to obtain calibration vibration data, calculating a filter to correlate the data, and applying this filter to process vibration data to estimate the vibration component of the parameter of interest, thereby correcting for vibrations during the lithographic process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single sensor is used to measure vibrations, then the device complexity is reduced, but the measurement precision deteriorates because the sensor data does not accurately represent vibrations at all components
Solution Approach 1:
The patent introduces a filter as an intermediary element that processes vibration data from a single sensor to estimate vibrations at other components. The filter acts as a mediator that transforms the single sensor's measurements into comprehensive vibration information for multiple components, resolving the contradiction between using one sensor and achieving multi-point measurement accuracy.
Solution Approach 2:
The patent creates a virtual copy of multi-sensor vibration data by using a filter to generate estimated vibration data from a single sensor. This copying approach allows the system to simulate what multiple sensors would measure without actually deploying multiple physical sensors, thereby maintaining measurement precision while reducing device complexity.
2Measurement precision
If multiple sensors are deployed to measure vibrations at different components, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The patent extracts only the essential vibration measurement function by using a single sensor combined with a filter, rather than deploying multiple sensors. This extraction approach removes unnecessary sensor components while preserving the core measurement capability through signal processing, thereby reducing device complexity while maintaining measurement precision.
3Manufacturing precision
If vibration compensation is applied using uncorrected sensor data, then the processing speed is maintained, but the manufacturing precision deteriorates due to vibration errors
Solution Approach 1:
The patent performs preliminary calibration to determine the filter characteristics before actual lithographic processing. This preliminary action allows the system to establish accurate vibration compensation parameters in advance, ensuring that the filter is optimized for the specific apparatus. This pre-calibration approach improves manufacturing precision without adding complexity during the actual processing operation.
Solution Approach 2:
The patent implements a feedback mechanism where vibration data from sensors is processed through a filter to generate compensation signals that are applied to correct for vibrations during pattern transfer. The feedback loop continuously adjusts the compensation based on actual vibration measurements, improving manufacturing precision while maintaining a relatively simple system architecture.
Data Source
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AI summary
A method involving obtaining first calibration vibration data relating to vibrations of the lithographic apparatus from a sensor that is part of the lithographic apparatus and obtaining second calibration vibration data, the second calibration vibration data being a component of first parameter data of the lithographic apparatus. A filter is calculated from the first and second calibration vibration data, the filter being such that when applied to the first calibration vibration data, its output correlates closer with the second calibration vibration data. The filter can then be applied to vibration data obtained using the first sensor to obtain an estimate of a vibration component of the first parameter data during the lithographic process.