Lithographic Stage Position Calibration via Extended Pattern Measurement
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Solution Overview
Problem
Conventional lithographic apparatuses face challenges in accurately calibrating stage positions due to long calibration times and loss of accuracy when stitching together calibration results across different frequency bands, particularly in detecting properties of substrates and performance measurements.
Innovation Solution
A method involving the projection of a pattern onto a substrate while moving it relative to the patterning device to create an extended pattern, allowing for measurement of the pattern's position perpendicular to the projection direction, thereby deriving a calibration of the stage position from these measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional encoder measurement systems are used to measure stage position, then position measurement capability is provided, but calibration time becomes excessively long and accuracy is lost when stitching calibration results across frequency bands
Solution Approach 1:
The patent transforms the calibration approach by projecting a two-dimensional pattern and extending it in one direction to create an extended pattern, then measuring positions in the perpendicular direction. This dimensional transformation allows simultaneous calibration across multiple frequency bands without sequential stitching, resolving the time-loss contradiction while maintaining measurement precision.
2Measurement precision
If multiple calibrations are performed across different frequency bands to improve measurement accuracy, then comprehensive calibration coverage is achieved, but the calibration process becomes time-consuming and accuracy is lost due to stitching errors
Solution Approach 1:
The patent merges multiple calibration operations into a single unified process by creating an extended pattern that encompasses multiple frequency bands simultaneously. The measurement system captures all frequency band information in one measurement pass, eliminating the need for sequential calibrations and their associated stitching errors, thus improving both accuracy and productivity.
3Loss of information
If detailed information about substrate properties and apparatus performance is detected using conventional methods, then comprehensive performance data is obtained, but the detection process becomes increasingly time-consuming
Solution Approach 1:
The patent enables continuous detection of substrate properties and apparatus performance by creating extended patterns that allow uninterrupted measurement across the entire measurement area. The methodology eliminates the need for repeated discrete measurements by providing comprehensive information from a single continuous measurement process, reducing detection time while maintaining information completeness.
Data Source
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AI summary
A detection method for detecting a property of an extended pattern formed by at least one line generally extending in a first direction. The extended pattern is formed on a substrate or on a substrate table and preferably extends over a length of at least 50x the width of the line. The extended pattern is focus sensitive. The detection method includes moving the substrate table in a first direction and measuring along that first direction a property of the extended pattern. The property can be a result of a physical property of the extended pattern in a second direction perpendicular to the first direction. In a next step a calibration of the substrate table position can be derived from the measured position of the extended pattern.