Free Electron Laser EUV Power Fluctuation Control
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Solution Overview
Problem
Existing free electron lasers face challenges in controlling the power fluctuations of EUV radiation, which affects the consistency of the exposure dose delivered to lithographic substrates, leading to inconsistent pattern formation in microelectronics manufacturing.
Innovation Solution
A feedback-based control loop is implemented to monitor and adjust the power of the EUV radiation generated by the free electron laser, using sensors to measure parameters like radiation power and electron current, and applying variable attenuation to ensure consistent exposure, with faster response rates to smooth out fluctuations quickly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a free electron laser is used to generate EUV radiation for lithography, then smaller features can be formed on substrates, but power fluctuations in the EUV radiation affect the consistency of exposure dose
Solution Approach 1:
The patent implements a feedback control system that monitors EUV radiation power in real-time and adjusts the electron beam parameters accordingly. Sensors detect power fluctuations and feed this information back to control the electron source and accelerator, dynamically compensating for variations to maintain consistent exposure dose on the substrate
Solution Approach 2:
The system dynamically adjusts electron beam parameters including current, energy, and bunching characteristics to compensate for power fluctuations. By changing these parameters in response to detected variations, the system maintains stable EUV output power and consistent exposure dose despite inherent instabilities in the free electron laser process
2Device complexity
If the feedback loop operates at low frequency, then the system is simpler to implement, but EUV radiation power fluctuations cannot be smoothed quickly enough during the 1 ms exposure time
Solution Approach 1:
The system performs preliminary measurements and adjustments before the actual exposure occurs. By characterizing power fluctuations and pre-adjusting electron beam parameters, the system prepares compensatory actions in advance that take effect during the 1 ms exposure window, ensuring dose consistency without requiring ultra-high-speed feedback during exposure itself
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
The method significantly improves the consistency of the EUV radiation dose delivered to substrates, ensuring more precise and reliable pattern formation by effectively reducing power fluctuations and maintaining a constant wavelength.
Implementation Method 1
an undulator arranged to receive the electron beam and guide it along a periodic path so that the electron beam interacts with radiation within the undulator, stimulating emission of radiation and providing a radiation beam
Data Source
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AI summary
A method of patterning lithographic substrates, the method comprising using a free electron laser to generate EUV radiation and delivering the EUV radiation to a lithographic apparatus which projects the EUV radiation onto lithographic substrates, wherein the method further comprises reducing fluctuations in the power of EUV radiation delivered to the lithographic substrates by using a feedback-based control loop to monitor the free electron laser and adjust operation of the free electron laser accordingly.