Multi-Plane Mirror Cooling for EUV Thermal Distortion Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
EUV mirrors in projection lenses experience thermally induced deformations and aberrations due to heating from absorbed radiation, which existing temperature regulation methods fail to adequately address, especially due to spatial temperature distribution and sensor inaccuracies.
Innovation Solution
An optical system with temperature control zones in different planes within the mirror substrate, allowing independent temperature setting and fluid cooling, utilizing the bimetal effect to deform the mirror surface precisely and compensate thermal distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single temperature sensor is used to regulate mirror temperature, then the device complexity is reduced, but the manufacturing precision deteriorates due to insufficient temperature control accuracy
Solution Approach 1:
The mirror substrate is divided into multiple temperature control zones (first, second, and third zones) with independent temperature control, allowing localized temperature regulation to achieve precise control of mirror surface deformation without requiring a single complex sensing system
Solution Approach 2:
Different regions of the mirror substrate are assigned different temperature control characteristics, with each zone having its own heating element and temperature control, enabling localized compensation of thermal deformations to improve manufacturing precision
2Manufacturing precision
If multiple temperature sensors are distributed across the mirror substrate, then the manufacturing precision improves through better temperature monitoring, but the device complexity increases
Solution Approach 1:
The mirror substrate is divided into multiple temperature control zones (first, second, and third zones) with independent temperature control, allowing localized temperature regulation to achieve precise control of mirror surface deformation without requiring a single complex sensing system
Solution Approach 2:
A control unit serves as an intermediary that receives temperature information from multiple sensors and coordinates the heating elements across different zones, simplifying the overall control architecture while maintaining precise temperature distribution control
3Stability of the object's composition
If the mirror substrate material has high thermal conductivity, then the temperature uniformity improves, but the manufacturing precision deteriorates due to inability to create localized temperature gradients for deformation control
Solution Approach 1:
The mirror substrate is divided into multiple temperature control zones (first, second, and third zones) with independent temperature control, allowing localized temperature regulation to achieve precise control of mirror surface deformation without requiring a single complex sensing system
Solution Approach 2:
Different regions of the mirror substrate are assigned different temperature control characteristics, with each zone having its own heating element and temperature control, enabling localized compensation of thermal deformations to improve manufacturing precision
4Manufacturing precision
If active heating is applied to maintain zero-crossing temperature, then the manufacturing precision improves by preventing thermal deformation, but the device complexity increases due to additional heating arrangements
Solution Approach 1:
The mirror substrate is divided into multiple temperature control zones (first, second, and third zones) with independent temperature control, allowing localized temperature regulation to achieve precise control of mirror surface deformation without requiring a single complex sensing system
Solution Approach 2:
The heating elements are integrated directly into the mirror substrate structure, merging the heating function with the substrate itself to reduce device complexity while maintaining precise temperature control capability
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
Precise control of mirror surface deformation to correct thermal distortions, enhancing imaging quality by providing an additional degree of freedom in wavefront adjustment, even with complex thermal profiles.
Implementation Method 1
a cooling fluid with a variably settable cooling-fluid temperature can flow
Implementation Method 2
the EUV mirrors can heat up and can undergo an associated thermal expansion or deformation
Implementation Method 3
the use of a heating arrangement, for example on the basis of infrared radiation
Data Source
AI summary
An optical system, for example in a microlithographic projection exposure apparatus, comprises a mirror and a temperature-regulating device. The mirror has an optical effective surface and a mirror substrate. A plurality of temperature-regulating zones are arranged in the mirror substrate. The temperature-regulating device is used to adjust the temperatures present in each of the temperature-regulating zones independently of one another. The temperature-regulating zones are arranged in at least two planes at different distances from the optical effective surface. The temperature-regulating zones in the at least two planes are configured as cooling channels through which, independently of one another, a cooling fluid at a variably adjustable cooling fluid temperature is able to flow. A method for operating such an optical system is provided.