EUV Optical Element Support via Distributed Clamping Units
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Solution Overview
Problem
In extreme ultraviolet (EUV) microlithographic systems, the transition to reflective optical systems with high numerical aperture poses challenges in maintaining imaging accuracy and stability due to the large and heavy optical units, which require robust yet adjustable support systems that can withstand shock loads and allow for easy replacement of optical elements.
Innovation Solution
A microlithographic optical arrangement using more than three separate holding units with clamping connections distributed along the circumference, allowing for robust shock load resistance and simple replaceability, with each holding unit establishing a separate clamping connection to distribute loads and reduce the maximum load on individual units, thereby simplifying the design and enhancing safety against shock loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a three-point support system is used to support optical units, then the optical element can be supported with minimal parasitic stresses, but the system becomes vulnerable to shock loads as the main load falls on a single holding unit
Solution Approach 1:
The support system is divided into multiple independent holding units (more than three) distributed around the optical element's circumference. Each holding unit independently carries a portion of the load, segmenting the overall support function to distribute shock loads rather than concentrating them on a single point.
Solution Approach 2:
The system transitions from a three-point support configuration to a multi-point support configuration with more than three holding units. This parameter change in the number of support points transforms the load distribution characteristics, enabling shock load resistance while maintaining minimal parasitic stresses through uniform distribution.
2Strength
If more than three holding units are used to distribute shock loads, then the maximum load on individual units is reduced, but the device complexity increases
Solution Approach 1:
The support function is segmented into multiple independent holding units distributed around the optical element. This segmentation allows the total load to be divided among more units, reducing the maximum load on any single unit while improving overall shock load resistance.
Solution Approach 2:
The holding units are arranged in a circumferential distribution around the optical element, utilizing the circumferential dimension to distribute loads uniformly. This spatial arrangement in another dimension allows for effective load distribution without increasing the radial or axial complexity of individual holding units.
3Measurement precision
If heavy optical units are used to achieve high numerical aperture, then imaging accuracy is improved, but the optical units become difficult to replace and adjust
Solution Approach 1:
The support system uses multiple separate holding units that can independently engage and disengage from the optical element. This segmentation of the support function allows for easy replacement and adjustment of the optical unit, as each holding unit can be independently operated without affecting the others.
Solution Approach 2:
The holding units are designed with dynamic engagement capabilities, allowing them to be easily attached and detached. This dynamic design enables the heavy optical units to be readily replaced and adjusted during operation or maintenance, overcoming the difficulty associated with their weight.
Data Source
AI summary
An optical arrangement of an imaging device for microlithography, particularly for using light in the extreme UV range, includes an optical element and a holding device for holding the optical element. The optical element includes an optical surface and defines a plane of main extension, in which the optical element defines a radial direction and a circumferential direction. The holding device includes a base element and more than three separate holding units. The holding units are connected to the base element and arranged in a manner distributed along the circumferential direction and spaced apart from one another. The holding units hold the optical element with respect to the base element. Each of the holding units establishes a clamping connection between the optical element and the base element. The clamping connection for each holding unit is separate from the clamping connections of the other holding units.