Lithography Stage Position Correction via Magnetic Field Deformation Compensation
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Solution Overview
Problem
Conventional lithographic apparatuses face challenges in achieving satisfactory positioning accuracy, particularly due to deformations caused by spatially varying magnetic fields, which affect measurement accuracy in both in-plane and out-of-plane directions, impacting overlay and focus precision.
Innovation Solution
A lithographic apparatus with a stage movable within a spatially varying magnetic field, utilizing a second position measurement system to provide a correction signal for the first measurement signal, thereby compensating for deformations and improving positioning accuracy by using a data processing device to correct the initial measurement signal based on the second measurement signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a position measurement system is used to measure stage position relative to reference structure, then positioning information is obtained, but measurement accuracy deteriorates due to stage deformations caused by spatially varying magnetic fields
Solution Approach 1:
A second position measurement system is introduced as an intermediary to measure the position of the stage relative to the magnet structure. This secondary measurement enables correction of the first measurement system's inaccuracies caused by magnetic field deformations, without requiring changes to the primary measurement approach.
Solution Approach 2:
The system uses feedback from the second position measurement system to correct the first measurement signal. The correction value, derived from the difference between expected and actual magnet structure position, is applied to compensate for deformation-induced measurement errors in real-time.
2Adaptability or versatility
If the magnet structure is moved relative to the reference structure and stage, then magnetic field positioning is achieved, but stage deformation increases affecting measurement accuracy
Solution Approach 1:
The system continuously monitors the actual position of the magnet structure using the second position measurement system and compares it with the expected position. Correction values are generated based on this feedback and applied to compensate for stage deformations, maintaining manufacturing precision despite magnetic field positioning activities.
Solution Approach 2:
The system replaces purely mechanical positioning with a hybrid approach that uses magnetic fields for positioning while incorporating sensor-based correction. This substitution allows the system to achieve both the adaptability of magnetic positioning and the precision required for manufacturing.
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
Enhances positioning accuracy by accounting for deformations caused by the magnetic field, leading to improved overlay and focus precision, meeting future demands in lithography.
Implementation Method 1
an magnet structure to provide a spatially varying magnetic field in at least a part of the motion range
Data Source
AI summary
A lithographic apparatus includes a stage to hold an object, the stage being moveable relative to a reference structure in a motion range; a magnet structure to provide a spatially varying magnetic field in at least a part of the motion range, the magnet structure being moveable relative to the reference structure and the stage; a first position measurement system to provide a first measurement signal corresponding to a position of the stage and/or the object in a measurement direction relative to the reference structure; a second position measurement system to provide a second measurement signal corresponding to a position of the stage relative to the magnet structure; and a data processor to correct the first measurement signal with a value dependent on the second measurement signal to provide a corrected first measurement signal representative of the position of the stage and/or the object relative to the reference structure in the measurement direction.