Gravitation Compensator for Optical Elements in EUV Lithography
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Solution Overview
Problem
Existing gravitation compensators for optical elements in projection exposure apparatuses, particularly in EUV systems, face challenges in maintaining positioning accuracy and stability over time, especially in hydrogen-containing atmospheres, due to high compensation forces and loads, which can lead to deformation and accuracy issues.
Innovation Solution
The use of a gravitation compensator with multiple magnetic compensator elements having different force-distance characteristic curves, arranged in series or parallel, and combined with mechanical spring elements, to maintain a constant compensation force over large displacements and long periods, while minimizing the influence of ambient conditions and aging effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If gravitation compensators are used to compensate for the weight force of optical elements, then the energy input into actuators is reduced, but the positioning accuracy of the optical elements is impaired
Solution Approach 1:
The gravitation compensator is divided into multiple independent compensator elements (first compensator element, second compensator element, etc.) that can be selectively activated. This segmentation allows the system to provide gravitation compensation when needed while maintaining the ability to achieve high positioning accuracy when the compensators are not active, thus resolving the contradiction between energy reduction and positioning accuracy.
Solution Approach 2:
The system dynamically switches between different operational states: with gravitation compensation active and with it inactive. The control system can selectively activate or deactivate individual compensator elements based on operational requirements, allowing the apparatus to optimize between energy consumption and positioning accuracy on a dynamic basis rather than being fixed in one state.
2Ease of operation
If gravitation compensators are used to enable movement of optical elements, then the supporting load on actuators is reduced, but the positional stability over long periods is adversely affected
Solution Approach 1:
By segmenting the gravitation compensation into multiple independent elements, the system can provide movement capability when needed while maintaining the option to disable compensation for high-stability operations. Each compensator element can be independently controlled, allowing the system to achieve both movement ease and positional stability depending on operational requirements.
3Force
If high compensation forces are used in gravitation compensators, then the weight force of large optical elements is compensated, but the positioning accuracy is impaired due to deformation
Solution Approach 1:
The high compensation force is distributed across multiple compensator elements rather than requiring a single high-force compensator. This segmentation allows the system to achieve the necessary total compensation force while each individual element operates at lower force levels, reducing deformation and maintaining positioning accuracy.
Solution Approach 2:
The compensator elements generate counteracting forces that balance the gravitational force on optical elements. By using multiple compensator elements working together, the system achieves the necessary counterweight effect to support heavy optical elements while maintaining positioning accuracy through distributed, controlled force application.
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 configuration ensures stable positioning accuracy and reduced deformation of optical elements, maintaining dimensional accuracy within tolerance ranges, even under high gravitational forces and in adverse atmospheres, by keeping the compensation force constant and minimizing changes in the bearing stiffness.
Implementation Method 1
The gravitation compensator (1000) includes at least two magnetic compensator elements (1001, 1002) having different force-distance characteristic curves
Implementation Method 2
combined with mechanical spring elements, to maintain a constant compensation force over large displacements and long periods
Data Source
AI summary
A gravitation compensator for mounting optical elements in a projection exposure apparatus and a corresponding projection exposure apparatus are disclosed. The gravitation compensator at least partly compensates for the weight force of a mounted optical element and simultaneously enables a change in the position of the optical element without the compensated weight force being altered in an impermissible manner during the change in position. This applies, in particular, to high weight forces which are to be compensated. Furthermore, the gravitation compensator enables use in different atmospheres and the compensation of corresponding aging effects.