Liquid Cooled EUV Reflector With Adaptive Thermal Zones
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical elements in EUV illumination systems experience thermally induced deformations due to uneven heat distribution caused by varying radiation intensity and absorption, leading to unwanted distortions during operation.
Innovation Solution
The implementation of a cooling system with separate cooling circuits and locally and temporally adaptive cooling zones, utilizing cooling channels and bodies with varying geometries and contact areas, to manage heat distribution and prevent deformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If uniform cooling is applied to the optical element, then the overall temperature is reduced, but the locally different heat distribution cannot be compensated, resulting in residual deformations
Solution Approach 1:
The cooling component is divided into multiple cooling zones with separate cooling circuits, allowing independent temperature control in different regions of the optical element. This segmentation enables localized cooling adjustments to match the spatially varying heat distribution from EUV radiation absorption.
Solution Approach 2:
Each cooling zone is equipped with adjustable cooling parameters (flow rate, temperature) that can be independently optimized for the local heat generation characteristics. This local quality approach allows precise compensation of thermal deformations in high-absorption regions while avoiding over-cooling in low-absorption areas.
2Device complexity
If the cooling system is simplified to a single cooling circuit, then the device complexity is reduced, but the ability to adapt to changing illumination settings and local heat distributions is lost
Solution Approach 1:
The cooling system incorporates dynamically adjustable parameters for each cooling zone, allowing real-time adaptation to changing illumination settings (annular, dipole, quadrupole, quasar modes). The control system can modify cooling intensity and distribution in response to varying radiation patterns and absorption characteristics.
Solution Approach 2:
The multi-zone cooling system serves multiple functions: it cools different regions independently, adapts to various illumination modes, compensates for temporal heat accumulation, and maintains optical element stability under diverse operating conditions. This universal cooling approach replaces the need for multiple specialized cooling systems.
3Power
If cooling channels with large contact areas are used, then the cooling efficiency is increased, but the spatial resolution of cooling control is reduced
Solution Approach 1:
The cooling component is divided into multiple cooling zones with distinct cooling circuits, enabling independent control of cooling intensity in different spatial regions. This segmentation provides the spatial resolution needed to match the non-uniform heat distribution from EUV absorption while maintaining adequate cooling efficiency in each zone.
Solution Approach 2:
The system adjusts cooling parameters (flow rate, temperature, channel geometry) in each cooling zone to optimize the balance between cooling efficiency and spatial resolution. By varying these parameters locally, the system achieves precise thermal control without requiring excessively fine segmentation that would reduce cooling effectiveness.
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 effectively reduces thermally induced deformations by providing spatially resolved cooling, maintaining optical element stability and ensuring precise control over temperature distribution, even under changing illumination settings.
Implementation Method 1
use is made of at least one cooling component which is connected to at least two separate cooling circuits
Implementation Method 2
The optically active surface can be cooled to a greater extent in at least one partial region than in a further partial region
Implementation Method 3
Depending on the magnitude of the absorption of EUV radiation, the energy input at the optical elements can be locally different
Implementation Method 4
IR radiation from other optical elements or from mechanical components can furthermore also impinge on the optical element under consideration and can be wholly or partly absorbed there
Implementation Method 5
at least one cooling component which is connected to at least two separate cooling circuits
Data Source
AI summary
The invention relates to an optical element for a projection exposure apparatus for semiconductor lithography comprising an optically active surface and at least one cooling component for cooling the optical element, wherein the cooling component is connected to at least two separate cooling circuits and embodied in such a way that the optically active surface can be cooled to a greater extent in at least one partial region than in a further partial region. The invention furthermore relates to a projection exposure apparatus comprising an optical element according to the invention.