EUV Light Source Separation Device for Interference Radiation
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Solution Overview
Problem
Existing EUV light sources face challenges in managing interference radiation, which causes undesirable effects such as heating of optical elements and thermal lens effects, particularly in space-constrained systems with separate radiation guidance devices for pre-pulse and main pulse laser beams.
Innovation Solution
Incorporating a separation device within the pre-pulse radiation system that reflects or focuses interference radiation back into the radiation generation chamber or into a jet trap, utilizing wavelength-dependent optical elements such as dichroitic mirrors to separate pre-pulses from interference radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a separate pre-pulse beam guiding device is used, then the pre-pulse laser beam can be guided independently, but interference radiation enters the pre-pulse beam guiding device causing heating and thermal lens effects
Solution Approach 1:
The patent extracts the harmful interference radiation from the pre-pulse beam path by introducing a separation device (wavelength-selective element) that spatially separates the pre-pulse laser beam from the interference radiation. The separation device reflects the interference radiation into a beam trap while allowing the pre-pulse beam to pass through, thereby removing the harmful factor without affecting the independent beam guidance capability
Solution Approach 2:
The patent converts the harmful interference radiation into a beneficial configuration by directing it into a beam trap where it is harmlessly absorbed. The separation device redirects the interference radiation that would otherwise cause heating and thermal lens effects into a dedicated absorption path, transforming a harmful factor into a controlled energy dissipation mechanism
2Object-affected harmful factors
If a beam trap is added to remove interference radiation, then heating effects are reduced, but the installation space requirement increases
Solution Approach 1:
The patent merges the beam trap functionality with the existing optical bench or housing structure of the pre-pulse beam guiding device. By integrating the beam trap into the available space within the optical path structure rather than adding it as a separate external component, the solution reduces the additional installation space requirement while maintaining the ability to capture and absorb interference radiation
Solution Approach 2:
The patent utilizes the vertical or depth dimension within the existing optical bench structure to accommodate the beam trap, rather than expanding the horizontal footprint. By positioning the beam trap in the available vertical space or within the depth of the optical housing, the solution effectively adds the radiation removal functionality without proportionally increasing the overall installation area
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 solution effectively mitigates the adverse effects of interference radiation on the pre-pulse radiation control device, while also optimizing space usage by eliminating the need for additional installation space for a jet trap, thereby enhancing the performance and reliability of the EUV light source.
Implementation Method 1
the pre-pulse beam guiding device (7) has at least one separation device (22) which is designed to reflect interference radiation entering the pre-pulse beam guiding device (7) from the radiation generation chamber (2) in at least one wavelength range which does not include the at least one pre-pulse wavelength (1030 nm), in a focused manner back into the radiation generation chamber (2) or in a focused manner into at least one beam trap (24)
Implementation Method 2
utilizing wavelength-dependent optical elements such as dichroitic mirrors to separate pre-pulses from interference radiation
Implementation Method 3
reflect interference radiation entering the pre-pulse beam guiding device (7) from the radiation generation chamber (2) in at least one wavelength range which does not include the at least one pre-pulse wavelength (1030 nm), in a focused manner back into the radiation generation chamber (2) or in a focused manner into at least one beam trap (24)
Implementation Method 4
The pre-pulse(s) serve to prepare the droplet for irradiation with the main pulse, in particular to heat the droplet, expand it, vaporize it, and/or generate a plasma
Implementation Method 5
The subsequent irradiation of each droplet with a main pulse serves to convert the target material into the plasma state, resulting in the emission of EUV radiation
Implementation Method 6
the target material is designed to emit EUV radiation as a result of the irradiation
Data Source
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AI summary
The invention relates to an EUV light source (1), comprising a supply device (3) for supplying a target material (4), a pre-pulse laser source (5) for emitting at least one pre-pulse laser beam (9) at at least one pre-pulse wavelength (λV), a main pulse laser source (6) for emitting a main pulse laser beam (10) at a main pulse wavelength (λH) different from the at least one pre-pulse wavelength (λV), a pre-pulse beam guiding device (7) for delivering the at least one pre-pulse laser beam (9) from the pre-pulse laser source (5) into a beam generation chamber (2) and for focused irradiation of the target material (4) inside the beam generation chamber (2) with in each case at least one pre-pulse (11) of the at least one pre-pulse laser beam (9), and a main pulse beam guiding device (8) for delivering the main pulse laser beam (10) from the main pulse laser source (6) into the beam generation chamber (2) and for focused irradiation of the target material (4) inside the beam generation chamber (2) with in each case a main pulse (12) of the main pulse laser beam (10). The target material (4) is designed to emit EUV radiation (19) following the irradiation. The pre-pulse beam guiding device (7) has at least one separation device (22) which is designed to reflect interfering radiation (21) entering the pre-pulse beam guiding device (7) from the beam generation chamber (2), in at least one wavelength range which does not include the at least one pre-pulse wavelength (λV), in a focused manner back into the beam generation chamber (2) or in a focused manner into at least one beam dump (24).