Actuator-Integrated Holding Element for EUV Optical Deformation Control
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Solution Overview
Problem
In extreme ultraviolet (EUV) microlithographic systems, achieving high imaging accuracy and maintaining it over the system's lifetime is challenging due to the large and heavy optical units, which require precise positioning and minimal deformation to avoid parasitic stresses and deformations.
Innovation Solution
The integration of actuator devices within the holding elements that form the interfaces between optical elements and support units allows for targeted deformation of optical elements with minimal parasitic influence on their rigid-body pose, using a combination of radial, tangential, and axial interface forces and moments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional refractive optical systems are used in EUV range, then imaging can be achieved, but the materials have too high absorbance to achieve acceptable imaging results with available light power
Solution Approach 1:
The patent replaces refractive optical systems with reflective optical systems for EUV imaging. This substitution is necessary because refractive materials in the EUV range have excessively high absorbance, making them incapable of transmitting sufficient light power for acceptable imaging results. Reflective systems eliminate the absorption loss inherent in refractive materials.
2Manufacturing precision
If heavy optical units are used to achieve high imaging accuracy, then positioning precision is improved, but the units become difficult to exchange and adjust
Solution Approach 1:
The patent divides the optical support system into modular components: a support structure with holding elements that can independently adjust the position and orientation of optical elements. This segmentation allows heavy optical units to be precisely positioned through coordinated adjustment of multiple holding elements while maintaining the ability to exchange and reconfigure individual components.
Solution Approach 2:
The patent implements dynamic adjustment capabilities through actuators that can modify the position and orientation of optical elements during operation. This dynamic support system maintains high imaging accuracy by continuously compensating for gravitational forces and vibrations while enabling easy exchange and adjustment of optical components.
3Manufacturing precision
If optical elements are supported with high precision to maintain spatial relationship, then imaging accuracy is improved, but parasitic stresses and deformations occur
Solution Approach 1:
The patent applies local quality by providing differentiated support characteristics at different locations of the optical element. Multiple holding elements with independent adjustment capabilities are distributed around the optical element, with each element providing localized support that collectively maintains overall spatial relationships while minimizing parasitic stresses through balanced local forces.
Solution Approach 2:
The patent implements feedback control through actuators that sense and compensate for gravitational forces, vibrations, and flow-induced vibrations acting on optical elements. This active feedback system maintains precise spatial relationships by continuously adjusting support forces to counteract external disturbances, preventing parasitic stresses and deformations.
4Ease of operation
If actuator devices are integrated within holding elements, then deformation control is simplified, but device complexity increases
Solution Approach 1:
The patent merges the actuator devices directly into the holding elements, combining the support function and deformation control function into a single integrated unit. This merging simplifies deformation control by eliminating the need for separate actuation mechanisms while the modular nature of the holding elements keeps the overall device complexity manageable.
Data Source
AI summary
An optical assembly of a microlithography imaging device comprises a holding device for holding an optical element. The holding device has a holding element having first and second interface sections. The first interface section for a first interface connecting the holding element and the optical element in an installed state. The second interface section forms a second interface connecting the holding element and a support unit in the installed state. The support unit connects the optical element to a support structure to support the optical element on the support structure via a supporting force. The holding device comprises an actuator device engaging on the holding element between the first and second interfaces. The actuator device acts on the holding element via a controller so that a specifiable interface deformation and/or a specifiable interface force distribution acting on the optical element is set on the first interface.