EUV Mirror Heating with IR Emitters
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Solution Overview
Problem
EUV mirrors in microlithographic projection exposure apparatuses experience thermal expansion and deformation due to radiation absorption, leading to imaging property degradation, and existing solutions like ultra-low thermal expansion materials and active heating/cooling methods are either costly or complex.
Innovation Solution
A heating arrangement using independently activatable IR emitters and a beam shaping unit to create segmented heating profiles on the optical element, matching the current illumination setting, thereby minimizing thermal deformations and aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If ultra-low thermal expansion material is used for the mirror substrate, then thermal expansion is minimized, but manufacturing cost increases
Solution Approach 1:
The patent changes the material parameter from ultra-low thermal expansion material to conventional material with non-zero thermal expansion coefficient, and compensates for the thermal expansion effect through active heating control, achieving the same stability outcome with lower manufacturing cost
Solution Approach 2:
The patent replaces the passive material-based solution (ultra-low thermal expansion material) with an active control-based solution (heating arrangement with sensors and controllers), substituting mechanical/material properties with control systems
2Stability of the object's composition
If direct electric heating or active direct cooling is used, then surface deformations are avoided, but structural outlay and installation space requirements increase
Solution Approach 1:
The patent replaces direct electric heating/cooling systems with an optical heating system using IR emitters, substituting electrical/mechanical infrastructure with optical components that require less structural support and have lower installation space requirements
Solution Approach 2:
The patent introduces IR radiation as an intermediary heating medium instead of direct contact heating systems, allowing thermal energy transfer through the optical path without requiring complex supply lines and structural supports
3Device complexity
If conventional heating arrangement with single IR emitter is used, then device complexity is low, but heating profile cannot be optimized for varying illumination settings
Solution Approach 1:
The patent divides the heating system into multiple independently controllable IR emitters positioned at different locations, allowing each emitter to be activated or deactivated based on the illumination setting, thereby achieving adaptable heating profiles without excessive complexity
Solution Approach 2:
The patent makes the heating arrangement dynamic by enabling independent activation and deactivation of IR emitters based on real-time illumination conditions, allowing the system to adapt to varying operational requirements
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 effectively reduces thermally induced deformations and aberrations by providing a homogeneous temperature distribution on the optical element, simplifying the production process and avoiding the complexity of traditional heating methods.
Implementation Method 1
a heating arrangement for heating this optical element and comprising a plurality of IR emitters for irradiating the optically effective surface with IR radiation
Implementation Method 2
As a result of absorption of the radiation emitted by the EUV light source among other reasons, the EUV mirrors can heat up
Implementation Method 3
at least one beam shaping unit for shaping the beam of the IR radiation steered onto the optically effective surface by the IR emitters
Implementation Method 4
the EUV mirrors can heat up and undergo an associated thermal expansion or deformation
Implementation Method 5
As a result of absorption of the radiation emitted by the EUV light source among other reasons, the EUV mirrors can heat up
Data Source
AI summary
An optical system includes at least one optical element which has an optically effective surface and which is designed for an operating wavelength of less than 30 nm. The optical system also includes a heating arrangement for heating this optical element and comprising a plurality of IR emitters for irradiating the optically effective surface with IR radiation. The IR emitters are activatable and deactivatable independently of each other to variably set different heating profiles in the optical element. The optical system further includes at least one beam shaping unit for shaping the beam of the IR radiation steered onto the optically effective surface by the IR emitters. The optical system also includes a multi-fiber head comprising a multi-fiber connector for connecting optical fibers. IR radiation from a respective one of the IR emitters is suppliable by way of each of these optical fibers.