EUV Polarization Characterization Using Transmissive Components
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Solution Overview
Problem
Characterizing the polarization properties of optical systems, particularly in high-resolution microlithographic projection exposure apparatuses with high numerical apertures, is challenging due to polarization-influencing effects, and existing methods face viability issues when implemented with reflective optical components in the EUV range.
Innovation Solution
A compact arrangement and method using polarisation state generators and detectors designed for operation in the transmission mode at wavelengths below 15 nm, ensuring constant polarisation-optical action over an angle spectrum, allowing for simultaneous measurement of exit polarisation states without the need for complex beam paths or actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reflective optical components are used in the EUV range for polarisation characterisation, then the measurement can be performed, but the structural space requirements become excessive and the implementation becomes non-viable
Solution Approach 1:
The patent inverts the conventional approach by using transmissive optical components instead of reflective components. This inversion allows the measurement system to operate in transmission mode, dramatically reducing the structural space requirements while maintaining the ability to characterise polarisation properties in the EUV range.
Solution Approach 2:
The patent changes the operational mode parameter from reflective to transmissive. By designing the optical components to operate in transmission mode rather than reflection mode, the system achieves compact structure while maintaining measurement capability for polarisation properties at EUV wavelengths.
2Area of stationary object
If transmission mode components are used for polarisation measurement in EUV range, then structural space is reduced, but the polarisation-optical action must remain constant over a wide angle spectrum
Solution Approach 1:
The patent applies local quality by designing the transmissive optical components with specific local characteristics that ensure uniform polarisation-optical action across different angles. The components are engineered to maintain consistent performance throughout the angle spectrum, addressing the uniformity requirement while benefiting from the compact structure.
3Manufacturing precision
If high numerical aperture is used in the imaging system, then imaging resolution is improved, but polarisation-influencing effects become more significant and harder to characterise
Solution Approach 1:
The patent introduces an intermediary measurement system that can characterise the polarisation properties of the high-aperture imaging system. By using transmissive components designed to work with the specific angle spectrum of high-aperture systems, the intermediary measurement apparatus can accurately detect and quantify polarisation-influencing effects without being compromised by the high numerical aperture.
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 reliable characterization of polarisation properties in the EUV range with a compact structure, avoiding the complexities of reflective components and allowing for time-efficient, accurate measurement of polarisation properties across larger aperture angles.
Implementation Method 1
at least one polarisation state generator (130) which sets a defined polarisation state of radiation incident on the optical system
Implementation Method 2
a polarisation state detector (140) adapted to measure the exit polarisation state of radiation issuing from the optical system
Data Source
AI summary
An arrangement for and a method of characterizing the polarization properties of an optical system, in particular an optical system of a microlithographic projection exposure apparatus. The arrangement includes at least one polarization state generator (130, 230, 330) which sets a defined polarization state of radiation incident on the optical system, and a polarization state detector (140, 240, 340) adapted to measure the exit polarization state of radiation issuing from the optical system, wherein the optical system is designed for a working wavelength of less than 15 nm, and wherein the polarization state generator and/or the polarization state detector are so designed that their polarization-optical action on an incident light beam is substantially constant over an angle spectrum of the light beam of at least 10°.