EUV Mirror Thermal Actuation via Access Passage
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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 quality issues, and existing methods for temperature measurement and actuation are not rapid or reliable, especially with non-homogeneous heat input from special illumination settings.
Innovation Solution
An arrangement using an access passage extending from a surface other than the optical effective surface of the mirror allows for mirror temperature measurement and thermal actuation via electromagnetic radiation, utilizing grazing incidence to minimize interference with the optical surface and employing a heat radiating mechanism for controlled heat dissipation and regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electromagnetic radiation is used for mirror temperature measurement and thermal actuation directly on the optical effective surface, then temperature control precision is improved, but the lithography process is adversely affected
Solution Approach 1:
The patent extracts the temperature measurement and thermal actuation function from the optical effective surface by introducing an access passage. The electromagnetic radiation is guided through this passage to interact with the mirror substrate at a location separate from the optical surface, thereby achieving temperature control without interfering with the lithography process.
Solution Approach 2:
The access passage serves as an intermediary structure that allows electromagnetic radiation to reach the mirror substrate for temperature measurement and actuation. This mediator enables the thermal control function while physically isolating it from the optical effective surface, preventing any adverse effects on the lithography process.
2Power
If electromagnetic radiation is propagated directly into the mirror substrate for thermal actuation, then thermal actuation effectiveness is improved, but the optical surface quality deteriorates
Solution Approach 1:
The patent segments the mirror structure into distinct functional zones: the optical effective surface for lithography and the substrate interior accessible via the access passage for thermal actuation. This segmentation allows independent optimization of each function - the optical surface maintains its quality while the substrate receives targeted thermal energy through the passage.
Solution Approach 2:
The thermal actuation function is extracted from the optical surface and relocated to the substrate interior through the access passage. This extraction ensures that the electromagnetic radiation for thermal control does not directly impinge on the optical surface, thereby preserving optical quality while maintaining thermal actuation effectiveness.
3Speed
If rapid temperature measurement is implemented, then thermal control response time is improved, but measurement reliability deteriorates due to non-homogeneous heat input
Solution Approach 1:
The patent replaces contact-based temperature measurement methods with electromagnetic radiation-based measurement through the access passage. This substitution enables rapid, non-contact temperature sensing that can respond quickly to thermal changes while avoiding the reliability issues associated with mechanical sensors in environments with non-homogeneous heat input.
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
Enables rapid and reliable mirror temperature measurement and thermal actuation without affecting the lithography process, effectively compensating for thermal deformations and maintaining imaging quality by using electromagnetic radiation with grazing incidence and controlled heat management.
Implementation Method 1
The electromagnetic radiation is reflected a plurality of times within the access passage
Implementation Method 2
the EUV mirrors experience a rise in temperature and therefore a thermal expansion or deformation, as a consequence of absorption of the radiation emitted by the EUV light source
Implementation Method 3
the arrangement is designed for mirror temperature measurement and/or thermal actuation of the mirror via electromagnetic radiation which is propagated along the access passage
Data Source
AI summary
The disclosure concerns an arrangement for mirror temperature measurement and/or thermal actuation of a mirror in a microlithographic projection exposure apparatus. The mirror has an optical effective surface and at least one access passage extending from a surface of the mirror, that does not correspond to the optical effective surface, in the direction of the effective surface. The arrangement is designed for mirror temperature measurement and/or thermal actuation of the mirror via electromagnetic radiation which is propagated along the access passage. The electromagnetic radiation is reflected a plurality of times within the access passage.