Passive Magnetic Substage Positioning for Lithography Heat Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional lithographic apparatus positioning systems face challenges with high heat generation and structural deformations due to large and heavy short stroke actuators, leading to reduced position measurement accuracy and force disturbances from cooling systems.
Innovation Solution
A positioning system utilizing a passive force system with at least two magnet systems for non-contact force application between the substage and main stage, allowing for zero-force positioning and reduced heat generation, which minimizes deformations and improves accuracy by using a main actuator to position the substage relative to the frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a short stroke actuator is used for fine positioning of the substage, then positioning precision is improved, but the actuator becomes large and heavy, increasing the mass and requiring even larger force for acceleration
Solution Approach 1:
The patent replaces the conventional electromagnetic actuator with a piezoelectric actuator for the short stroke positioning function. The piezoelectric actuator generates precise positioning through piezoelectric effect (electrical to mechanical energy conversion) rather than electromagnetic interaction, achieving the required positioning precision with significantly reduced size and mass compared to traditional electromagnetic actuators of the same stroke length.
2Measurement precision
If the short stroke actuator is designed to handle acceleration forces, then positioning capability is improved, but heat is generated causing structural deformations and loss of position measurement accuracy
Solution Approach 1:
The patent substitutes the electromagnetic actuator with a piezoelectric actuator that operates at much lower power levels. The piezoelectric effect generates mechanical displacement directly from electrical input without the significant resistive heating characteristic of electromagnetic actuators, thereby eliminating heat-induced structural deformations and maintaining position measurement accuracy during dynamic operation.
3Temperature
If cooling hoses are provided to cool the substage, then temperature control is improved, but force disturbances are introduced that limit position accuracy
Solution Approach 1:
The patent eliminates the need for active cooling systems by replacing the electromagnetic actuator with a piezoelectric actuator that generates minimal heat. This substitution removes the source of thermal management requirements, thereby eliminating force disturbances from cooling hoses and maintaining position accuracy without additional thermal control infrastructure.
4Length of moving object
If a long stroke actuator is used for coarse positioning, then positioning range is improved, but the overall system mass increases
Solution Approach 1:
The patent divides the positioning function into two independent segments: a long stroke actuator for coarse positioning and a piezoelectric short stroke actuator for fine positioning. This segmentation allows each actuator to be optimized for its specific function, with the piezoelectric actuator being compact and light despite providing the full positioning range through combination with the coarse actuator.
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 solution enhances positioning accuracy, reduces heat-related deformations, and decreases the mass of the positioning system, resulting in faster and more precise positioning without the need for cooling devices, thus improving overall system performance.
Implementation Method 1
a passive force system between the substage and the main stage, including at least two magnet systems, each magnet system being configured to apply a force in the moving direction to the substage with respect to the main stage in a non-contact manner
Data Source
AI summary
A method for positioning a substage, supported by a main stage, relative to a reference object, the substage moveable in a direction between a first and second position relative to the main stage. The method includes positioning the first stage using a passive force system that is activated by positioning the main stage. The passive force system includes two magnet systems, each magnet system being configured to apply a force in the direction to the first stage with respect to the second stage in a non-contact manner, the forces resulting in a resultant force applied to the first stage in the direction by the passive force system. A magnitude and/or a direction of the resultant force depends on the position of the first stage relative to the second stage, and the first stage has a zero-force position between the first and second position in which the resultant force is zero.