EUV Optical Element Deformation Actuator for Wavefront Correction
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Solution Overview
Problem
High numerical aperture EUV optical systems face challenges in maintaining imaging accuracy and reducing wavefront aberrations due to parasitic forces and uneven deformation in existing active wavefront correction methods, particularly in microlithography processes where feature sizes are below 7 nm and overlay accuracy is stringent.
Innovation Solution
A three-part deformation actuator concept is implemented, where a first and second actuator part are connected to different parts of the optical element, and a shared third actuator part generates forces that cancel out in one operating state, allowing for flexible and contactless deformation without introducing parasitic forces or moments, enabling precise wavefront correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing active wavefront correction methods are used in high numerical aperture EUV systems, then wavefront aberrations can be corrected, but parasitic forces and uneven deformation are introduced that compromise imaging accuracy
Solution Approach 1:
The optical element is divided into multiple independently controllable zones or segments, each equipped with its own actuator. This segmentation allows localized wavefront correction without requiring force application that would generate parasitic effects across the entire element, thereby maintaining imaging accuracy while avoiding harmful forces.
Solution Approach 2:
The patent replaces traditional mechanical actuation systems that apply physical forces with alternative mechanisms such as magnetic fields, electrostatic fields, or thermal expansion control. This substitution eliminates contact-based parasitic forces while still enabling precise deformation control for wavefront correction in high numerical aperture EUV optical systems.
2Measurement precision
If existing active wavefront correction methods are used, then wavefront aberrations can be corrected, but uneven deformation occurs that reduces imaging quality
Solution Approach 1:
The optical element is designed with spatially varying properties, such as non-uniform thickness, material composition, or actuator distribution, that compensate for expected deformation patterns. This local quality variation ensures that when actuators apply correction forces, the resulting deformation is uniformly distributed across the wavefront, preventing imaging quality degradation while maintaining correction accuracy.
Solution Approach 2:
The system employs dynamic control strategies where actuator forces are continuously adjusted based on real-time feedback from wavefront sensors. This dynamic adaptation allows the system to compensate for varying deformation patterns and maintain uniform wavefront correction across different operating conditions, preventing uneven deformation that would compromise imaging quality.
3Measurement precision
If complex deformation control mechanisms are implemented to maintain imaging accuracy, then wavefront aberrations are corrected, but device complexity increases
Solution Approach 1:
The optical element is designed with multi-functional capabilities where a single integrated structure serves both as the optical component and the deformation control mechanism. For example, the optical element itself may contain embedded actuators or smart materials that enable wavefront correction without requiring separate complex control systems, thereby maintaining imaging accuracy while reducing overall device complexity.
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 enhances imaging accuracy and reduces wavefront aberrations while simplifying the deformation process, maintaining long-term reliability and reducing the effort involved in maintaining imaging quality in EUV microlithography systems.
Implementation Method 1
The first and second force generating units each include a first and second coil unit, respectively, and a shared magnet unit. The first and second coil units are configured to generate the first and second deformation forces in response to a control signal in a contactless manner.
Data Source
AI summary
Optical modules used in exposure processes, in particular to optical modules of microlithography systems, are disclosed. Methods for deforming an optical element of an optical module as well as to optical imaging arrangements, optical imaging of methods and a method of manufacturing an optical element, are also disclosed. The disclosed technology may be used in the context of photolithography processes for fabricating microelectronic devices, in particular semiconductor devices, or in the context of fabricating devices, such as masks or reticles, used during such photolithography processes.