Patterning Device–Substrate Alignment With Moving Optical Components
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing alignment methods for patterning devices and substrates in lithographic apparatuses using moveable optical components are inaccurate due to cyclic errors in position measurement systems, leading to overlay errors during patterning processes.
Innovation Solution
A method involving the displacement of moveable optical components along predetermined trajectories during alignment measurements to mitigate cyclic errors in position measurement systems, allowing for accurate spatial alignment by averaging out measurement inaccuracies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If moveable optical components are used in the optical path during alignment measurement, then the alignment system becomes more flexible and adaptable, but cyclic errors in position measurement systems cause inaccuracies in spatial alignment
Solution Approach 1:
The patent applies periodic action by performing multiple alignment measurements at different positions of the moveable optical components and combining these measurements. The alignment process involves taking measurements at several discrete positions and using mathematical combination (such as averaging or optimization algorithms) to derive the final alignment parameters, thereby converting a single inaccurate measurement into a set of periodic measurements that collectively eliminate cyclic errors.
Solution Approach 2:
The patent implements feedback by using the results from multiple measurements at different optical component positions to refine and correct the alignment determination. The system feeds back the measurement data from various positions into an optimization algorithm that calculates the most accurate alignment parameters, ensuring that the final alignment compensates for cyclic errors present in individual measurements.
2Measurement precision
If multiple measurements are taken at different positions of moveable optical components, then measurement accuracy improves through error averaging, but the alignment process time increases
Solution Approach 1:
The patent applies preliminary action by pre-planning and pre-positioning the moveable optical components at predetermined measurement positions before taking alignment measurements. The system prepares the measurement sequence in advance, positioning components at optimal locations for each measurement step, which streamlines the measurement process and reduces unnecessary adjustments during the actual alignment measurement phase.
Solution Approach 2:
The patent utilizes parameter changes by systematically varying the position parameters of the moveable optical components during measurements. By changing positional parameters to predetermined values and combining measurement results from these different parameter states, the system achieves accurate alignment while managing measurement time through controlled parameter variation rather than exhaustive searching.
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 method provides improved accuracy in spatial alignment between patterning devices and substrates by reducing the impact of cyclic errors in position measurement systems, ensuring precise patterning even with moveable optical components.
Implementation Method 1
projecting a radiation beam from the patterning device along the optical path
Implementation Method 2
projecting a radiation beam from the patterning device along the optical path
Data Source
AI summary
Method of spatially aligning a patterning device and a substrate, wherein the patterning device and the substrate are separated by an optical path including one or more moveable optical components, the method including: projecting a radiation beam from the patterning device along the optical path; performing a displacement of the one or more moveable optical components along a predetermined trajectory; determining an optical characteristic of the radiation beam as received by a sensor on a substrate table supporting the substrate at a plurality of instants during the displacement of the one or more moveable optical components; and spatially aligning the patterning device and the substrate based on the optical characteristic as determined at the plurality of instants.