Rotating Debris Mitigation for EUV Sensor Lifetime
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Solution Overview
Problem
EUV-radiation sources emit debris that contaminates sensors, leading to inaccurate measurements due to the deposition of tin particles and droplets, which reduces the transmission and accuracy of EUV radiation energy monitoring, especially when using rotating debris mitigation units that can block radiation and affect measurement precision.
Innovation Solution
A rotating debris mitigation unit with passages allowing straight radiation pass, where the radiation-sensitive element and guiding mirrors are fixed to the rotating unit, ensuring consistent radiation exposure and using a buffer gas to slow down debris particles, combined with multilayer mirrors and bandpass filters to maintain measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a debris mitigation unit is used to protect the sensor from contamination, then the sensor lifetime is extended, but the measurement precision deteriorates due to radiation blocking
Solution Approach 1:
The debris mitigation unit is designed to rotate about its central axis during operation. This dynamic configuration allows the unit to periodically move out of the radiation path, enabling the radiation-sensitive element to receive uninterrupted EUV radiation for accurate measurements while still providing debris protection during other rotation phases
Solution Approach 2:
The rotating debris mitigation unit creates periodic openings in the radiation path as it rotates. This periodic action allows bursts of EUV radiation to reach the sensor while maintaining continuous protection against debris, resolving the contradiction between protection and measurement accuracy
2Duration of action of stationary object
If a rotating debris mitigation unit is used to prevent droplet contamination, then the sensor lifetime is extended, but the measurement accuracy deteriorates due to blocked radiation
Solution Approach 1:
The rotating debris mitigation unit dynamically adjusts its position to periodically allow radiation through while maintaining debris protection. This dynamic operation enables the system to achieve both droplet mitigation and accurate measurement
Solution Approach 2:
The rotating unit acts as an intermediary between the radiation source and sensor, mediating the conflict between debris protection and radiation transmission by selectively allowing radiation through during rotation
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 setup significantly extends the lifetime of sensors by preventing contamination and maintains measurement accuracy by ensuring consistent radiation exposure, allowing for precise EUV radiation energy monitoring and improved dose stability in EUV lithography applications.
Implementation Method 1
a buffer gas essentially transparent to EUV-radiation is supplied between the radiation source and the debris mitigation unit in order to slow down or stop atomic particles of the debris
Implementation Method 2
a radiation-sensitive element delivering an electrical signal dependent on an energy of incident radiation
Implementation Method 3
two multilayer mirrors to further limit the desired wavelength range
Data Source
Figure 1~2
AI summary
The present invention relates to a measurement setup for measuring radiation energy, in particular of EUV-radiation and/or soft X-rays. The measurement setup comprises a debris mitigation unit (2, 14) with several passages allowing a straight pass of incoming radiation and a radiation-sensitive element (10, 15) delivering an electrical signal dependent on an energy of incident radiation. The radiation-sensitive element (10, 15) is arranged to measure a fraction of said incoming radiation after passing said debris mitigation unit (2, 14) at least partly. The debris mitigation unit (2, 14) of the present setup is mounted allowing a rotation around a central axis (8) of said debris mitigation unit (2, 14) during operation. Said radiation-sensitive element (10, 15) and/or one or several mirrors (11) guiding said fraction of said radiation to said radiation-sensitive element (10, 15) is/are fixed to said rotating debris mitigation unit (2, 14).