Shared Balance Mass System for Lithography Machine Stages
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Solution Overview
Problem
Current lithography machines face challenges with high structural size and mass due to the use of independent balance mass systems for workpiece and mask tables, leading to increased complexity, size, and weight, which affects accuracy and throughput.
Innovation Solution
A shared balance mass system is introduced, where a balance mass and anti-drift compensation apparatus support both the workpiece and mask stages, eliminating the need for additional supports and reducing overall mass and size by using a single system for both stages, with a movable countermass system to compensate for changes in center of gravity and tilting moments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If independent balance mass systems are used for workpiece and mask tables, then each table can be balanced independently, but the overall structural size and mass increase
Solution Approach 1:
The patent merges the balance mass systems of the workpiece table and mask table into a single shared system. The balance mass is divided into a first part supporting the workpiece table and a second part supporting the mask table, which are interconnected through a third part. This consolidation reduces the total mass and structural size while maintaining balance functionality for both tables.
Solution Approach 2:
The shared balance mass system serves multiple functions: it balances the workpiece table, balances the mask table, and provides a common support structure. The anti-drift and compensation apparatus further enhances this multi-functionality by compensating for gravitational effects and maintaining positional accuracy for both tables simultaneously.
2Reliability
If independent balance mass systems are used for workpiece and mask tables, then each table has dedicated support, but device complexity increases
Solution Approach 1:
By combining the balance mass systems into one shared structure with interconnected parts, the patent reduces the number of independent support structures needed. The first part, second part, and third part work together as an integrated system, simplifying the overall device architecture while maintaining dedicated support for each table.
3Volume of moving object
If a shared balance mass system is used, then structural compactness improves, but control complexity increases due to coupled movements
Solution Approach 1:
The anti-drift and compensation apparatus acts as an intermediary mechanism between the balance mass and the tables. It compensates for the coupling effects and gravitational drift, enabling independent control of the workpiece and mask tables despite their shared support structure. This mediator resolves the control complexity issue while maintaining the compact shared design.
4Measurement precision
If balance mass system is connected to base frame, then position initialization and tracking can be achieved, but reaction forces are transferred to base frame
Solution Approach 1:
The patent extracts the balance mass system from direct connection to the base frame by using floating support through air bearings. This separation allows the balance mass to counteract reaction forces without transferring them to the base frame, while the anti-drift and compensation apparatus maintains position accuracy through active compensation rather than rigid mechanical connection.
Data Source
AI summary
A balance mass system shared by a workpiece stage and a mask stage includes a balance mass and an anti-drift and compensation apparatus (16). The balance mass includes a first part (11) for mounting thereon a workpiece stage system, a second part (20) for mounting thereon a mask stage system, and a third part (14) for interconnecting the first part (11) and the second part (20). The first part (11) of the balance mass is floatingly supported on a base frame (1) of a lithography machine, and the third part (14) of the balance mass is in connection with the base frame (1) via the anti-drift and compensation apparatus (16). The anti-drift and compensation apparatus (16) is disposed in proximity to the center of gravity of the balance mass as a whole. This balance mass system can eliminate the need for using an additional support for the mask stage system and allow the construction of a lithography machine with a higher structural compactness, reduced size and weight, and reduced total mass of used balance masses.