EUV Lithography Mirror Weight Compensation via Dual Magnetic Devices
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Solution Overview
Problem
The weight compensating devices in EUV lithography apparatuses experience changes in compensating force over time due to aging of magnetic forces, leading to insufficient or excessive weight compensation, which is balanced by Lorentz actuators, causing constant current flow and potential heat-related issues affecting mirror positioning.
Innovation Solution
An arrangement using a first and second magnetic device, where the first magnetic force exceeds the weight and counteracts it, and the second magnetic force acts in the direction of the weight, ensuring the first magnetic force always equals the sum of the second magnetic force and the weight, eliminating the need for additional mounting forces and maintaining consistent weight compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a weight compensating device using permanent magnets is used to counteract the weight of the mirror, then the mirror can be positioned accurately, but the magnetic forces weaken over time due to aging, causing insufficient weight compensation
Solution Approach 1:
The patent changes the physical state of the magnetic material from permanent magnet to magnetizable material that can be actively magnetized and demagnetized. This allows the magnetic force parameters to be dynamically adjusted and reset, eliminating the aging-related force degradation that occurs with permanent magnets.
Solution Approach 2:
The patent replaces the passive permanent magnet system with an active electromagnetic system using magnetizable material and coil. This substitution enables dynamic control of the compensating force through electrical current, replacing the irreversible mechanical/magnetic aging process with a controllable electromagnetic field.
2Measurement precision
If Lorentz actuators are used to balance insufficient weight compensation, then positioning can be maintained, but constant current flow generates heat that adversely affects mirror positioning
Solution Approach 1:
The magnetizable material serves dual functions: it provides the primary weight compensating force through magnetic attraction to the permanent magnet, and it can be demagnetized to eliminate residual forces. This self-service capability eliminates the need for continuous corrective current from Lorentz actuators, thereby preventing heat generation.
Solution Approach 2:
The patent extracts the heat generation problem by eliminating the need for constant corrective current flow. By ensuring proper weight compensation through the magnetizable material system, the harmful thermal effect is removed from the positioning system.
3Adaptability or versatility
If a vertically displaceable ring of magnetically soft material is used to adjust the compensating force, then the force can be adjusted, but an additional mechanical component must be moved
Solution Approach 1:
The patent replaces the mechanical displacement of a magnetically soft ring with an electromagnetic approach using magnetizable material and coil. The magnetic force is adjusted by controlling the magnetization state through electrical current rather than mechanical movement, eliminating the need for additional moving mechanical components.
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 ensures consistent weight compensation over time by adjusting the magnetic forces of different materials to decrease at the same absolute value, maintaining precise positioning of mirrors without additional mechanical components or heat sources.
Implementation Method 1
a first magnetic device (204), which is designed to exert on the component (126) a first magnetic force (F1), which exceeds the weight (FG) of the component (126) and counteracts the weight (FG) of the component (126)
Implementation Method 2
a second magnetic device (206), which is designed to exert on the component (126) a second magnetic force (F2), which acts in the direction of the weight (FG) of the component (126)
Data Source
AI summary
An arrangement for a lithography apparatus has a component and a weight compensating device to compensate for a weight of the component. The weight compensating device includes a first magnetic device and a second magnetic device. The first magnetic device is designed to exert a first magnetic force on the component. The first magnetic force exceeds the weight of the component. The first magnetic force acts counter to the weight of the component. The second magnetic device is designed to exert a second magnetic force on the component. The second magnetic force acts in the direction of the weight of the component. The first magnetic force corresponds to the sum of the second magnetic force and the weight. The second magnetic device is designed to reduce the second magnetic force at the same time and by the same absolute value as the first magnetic force.