Actuator Module Frame Resonance Suppression in EUV Optics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In projection exposure apparatuses, particularly in the EUV range, manipulating the position of optical elements like mirrors is challenging due to the destabilization of position control circuits caused by reaction forces, which excite weakly damped resonances, leading to instability and precision issues.
Innovation Solution
The solution involves an arrangement where at least one actuator and one position sensor are mounted on a common module frame, mechanically attached to a reference frame such that the resonant frequencies of this attachment fall within 0.5 to 2 times the bandwidth of the position control circuit, allowing for precise positioning while damping attachment resonances without additional damping measures, and using two independent actuators to decouple forces from the reference frame, effectively suppressing reaction path dynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an actuator is used to position an element, then the position can be controlled, but reaction forces excite resonances that destabilize the control circuit
Solution Approach 1:
A decoupling element is introduced as an intermediary between the actuator and the reference frame. This decoupling element mechanically separates the reaction force path from the reference frame, preventing resonance excitation while maintaining positioning capability. The decoupling element acts as a mediator that allows force transmission to the element being positioned while isolating the reference frame from destabilizing reaction forces.
2Stability of the object's composition
If reaction masses are used to counteract reaction forces, then stability improves, but device complexity increases
Solution Approach 1:
The problematic reaction force path is extracted and separated from the main system. Instead of adding reaction masses to counteract forces, the decoupling element removes the reaction force transmission path to the reference frame, thereby eliminating the source of instability without adding complex counterbalancing mechanisms.
3Manufacturing precision
If the module frame is rigidly attached to the reference frame, then positioning accuracy improves, but reaction forces are transmitted causing instability
Solution Approach 1:
The mechanical attachment between the module frame and reference frame is designed with localized flexibility only where needed for resonance suppression. The decoupling element provides just enough compliance to prevent resonance excitation while maintaining sufficient rigidity elsewhere to ensure positioning accuracy. This selective application of flexibility resolves the contradiction between rigid attachment for precision and flexible attachment for stability.
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 approach enables precise and stable positioning of optical elements with minimal structural expenditure, achieving high controller bandwidth and suppressing reaction path effects, thus preventing stability problems and allowing for a compact, modular, and cost-effective architecture suitable for EUV and other optical systems.
Implementation Method 1
the resonant frequencies (ωMR) of this attachment, where ωB denotes the bandwidth of the position control circuit
Implementation Method 2
damping attachment resonances without additional damping measures
Data Source
AI summary
The disclosure relates to arrangements for manipulating the position of an element. An arrangement according has at least one actuator for each degree of freedom of the positional manipulation for exerting adjustable forces on the element, at least one position sensor for each degree of freedom of the positional manipulation for generating in each case a sensor signal that is characteristic of the position of the element, and at least one position controller, which in a position control circuit controls a force exerted on the element by the at least one actuator for the positioning of the element in dependence on the at least one sensor signal. At least one actuator and at least one position sensor are mounted on a common module frame.