Stage System Balance Mass Feed-Forward Vibration Control
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Solution Overview
Problem
Conventional metrology tools for measuring parameters like Overlay, Critical Dimensions, Film Thickness, and Refractive Index in lithographic processes face limitations due to high frame vibrations, which reduce throughput and accuracy.
Innovation Solution
A stage system with a balance mass and actuator to compensate for reaction forces, along with a cable arrangement that applies a compensatory feed-forward force to minimize vibrations, enhancing the stability and speed of the stage systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a balance mass is added to compensate reaction forces, then frame vibrations are reduced, but device complexity increases
Solution Approach 1:
A balance mass is introduced to counteract the reaction forces generated by the stage carrier during movement. The balance mass positioning actuator adjusts the position of the balance mass to maintain balance, thereby reducing frame vibrations caused by unbalanced reaction forces.
Solution Approach 2:
A cable arrangement is introduced as an intermediary element connected to both the stage carrier and the balance mass. This cable arrangement transmits the compensatory feed-forward force from the balance mass to the stage carrier, enabling coordinated movement and force compensation without direct mechanical coupling.
2Productivity
If stage movement speed is increased to improve throughput, then productivity increases, but frame vibrations increase
Solution Approach 1:
A feed-forward control mechanism is implemented where the balance mass positioning actuator proactively adjusts the balance mass position based on anticipated stage carrier movement. This preliminary action compensates for reaction forces before they fully manifest, reducing vibrations even at higher movement speeds.
Solution Approach 2:
The balance mass system continuously counteracts reaction forces during high-speed stage movement, enabling faster throughput while maintaining frame stability through dynamic force compensation.
3Measurement precision
If measurement accuracy is improved by reducing vibrations, then measurement precision increases, but device complexity increases
Solution Approach 1:
The balance mass and positioning actuator system reduces frame vibrations that would otherwise degrade measurement precision. By actively compensating for reaction forces, the system creates a more stable measurement environment without requiring complex vibration isolation infrastructure.
Solution Approach 2:
The cable arrangement serves as a flexible intermediary that transmits compensatory forces while accommodating the dynamic movement of the stage carrier, enabling vibration reduction for improved measurement accuracy without rigid mechanical constraints.
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
This solution reduces frame vibrations, allowing for faster and more accurate measurements, thereby improving the throughput and precision of metrology tools in lithographic processes.
Implementation Method 1
a balance mass positioning actuator for displacing the balance mass; wherein the stage system is operable to apply a compensatory feed-forward force to the balance mass which compensates for a cable arrangement force exerted by the cable arrangement
Implementation Method 2
a cable arrangement connected to the stage carrier for the supply of at least power to said stage carrier
Data Source
AI summary
Disclosed is a stage system and metrology apparatus comprising at least one such stage system. The stage system comprises a stage carrier for holding an object and a stage carrier positioning actuator for displacing the stage carrier. The stage system also comprises a balance mass to counteract a displacement of the stage carrier, and a balance mass positioning actuator for displacing the balance mass. A cable arrangement is connected to the stage carrier for the supply of at least power to said stage carrier. The stage system is operable to apply a compensatory feed-forward force to the balance mass which compensates for a cable arrangement force exerted by the cable arrangement.