Moving Mirror Set for Beam Path Compensation in Metrology
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Solution Overview
Problem
Lithographic projection systems face challenges in maintaining precise beam path alignment and measurement accuracy when dealing with moving objectives, particularly in systems with movable stages, which can lead to misalignment and compromised measurement quality.
Innovation Solution
A system comprising a mirror set with movable mirrors configured to maintain beam alignment and stability through controlled movements, allowing the objective to move in synchronization with the stage while keeping the beam's focus point stationary relative to the objective, utilizing angular ratios and static mirrors to compensate for stage movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the objective moves in synchronization with the movable stage, then the measurement system can accommodate moving objectives, but the beam path alignment and measurement accuracy deteriorate due to misalignment
Solution Approach 1:
A mirror set is introduced as an intermediary component between the beam source and the moving objective. The mirror set includes mirrors mounted on the movable stage that reflect and redirect the beam path. By positioning mirrors at specific angles (e.g., 45 degrees) on the moving stage, the system allows the objective to move while the beam path remains compensated and aligned through the reflective action of the mirrors, thus maintaining measurement precision despite objective movement.
2Reliability
If mirrors are mounted on the movable stage to redirect the beam, then the beam path can be compensated for stage movement, but the system complexity increases
Solution Approach 1:
The mirror set is merged with the movable stage structure, with mirrors directly mounted on the stage. This integration ensures that the mirrors move synchronously with the stage and objective, maintaining consistent geometric relationships. The mirrors are positioned and oriented such that their combined reflective action compensates for stage movement, providing reliable beam path compensation without requiring additional independent adjustment mechanisms, thus limiting the increase in system complexity.
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
Enables precise and stable beam path compensation, ensuring accurate measurements and alignment even with moving objectives, enhancing the measurement quality and reliability of metrology systems.
Implementation Method 1
The first mirror is configured to receive a beam at a first angle from an axis of the mirror set. The second mirror is configured to provide the beam at a second angle from the axis of the mirror set, the beam providing an output after reflection by the second mirror.
Data Source
AI summary
A mirror set having a first mirror, a second mirror, and a movable stage to which the mirror set is mounted to cause the first mirror and the second mirror to move together with the movable stage. The first mirror is configured to receive a beam at a first angle from an axis of the mirror set and the second mirror is configured to provide the beam at a second angle from the axis of the mirror set, the beam providing an output after reflection by the second mirror. Movement of the mirror set parallel to the axis results in a parallel shift of the output along the beam and movement of the mirror set perpendicular to the axis results in a perpendicular shift of the output perpendicular to the beam.