Optical Path Tube Gas Outlet Layout for EUV Debris Suppression
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Solution Overview
Problem
In optical path tubes where gas flow is not smooth, debris accumulation occurs, leading to a decrease in the amount of EUV light due to insufficient suppression of debris adhesion on optical members and gas accumulation.
Innovation Solution
A light source apparatus with an optical path tube featuring gas intake parts and multiple outlets to ensure uniform gas flow, including a first outlet on the plasma forming area side and a second outlet around the outer circumference, which discharges gas near the mirror, thereby preventing debris deposition on filters and maintaining EUV light intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If gas flow rate is increased to suppress debris adhesion, then debris suppression improves, but gas accumulation occurs in the optical path tube
Solution Approach 1:
The optical path tube is divided into multiple sections with different gas intake and outlet configurations. Gas intake parts are positioned at specific locations (e.g., lower section) while outlets are positioned at different heights (e.g., upper section), creating segmented flow zones that prevent dead spots and ensure continuous gas movement through the entire tube volume.
Solution Approach 2:
Gas flow is introduced not only from the end of the optical path tube but also from the side walls at multiple positions. This multi-dimensional gas introduction approach ensures comprehensive coverage of the tube interior, preventing debris accumulation on optical members while maintaining smooth gas flow without excessive pressure buildup.
2Quantity of substance
If gas flow rate is decreased to prevent gas accumulation, then gas accumulation is reduced, but debris adhesion suppression deteriorates
Solution Approach 1:
Gas is introduced at multiple positions along the optical path tube before the plasma generation event occurs. This preliminary gas flow establishment ensures that when plasma and debris are generated, the gas flow is already in place to immediately carry debris away from optical members, preventing adhesion while maintaining appropriate flow rates.
Solution Approach 2:
The optical path tube structure itself acts as an intermediary by providing multiple gas intake ports and outlet ports that mediate the gas flow distribution. This structured approach ensures uniform gas distribution throughout the tube, maintaining effective debris suppression at optimized flow rates that prevent both accumulation and adhesion.
3Device complexity
If single outlet configuration is used, then device complexity is reduced, but gas flow uniformity deteriorates
Solution Approach 1:
Instead of a single outlet, the system uses multiple outlet ports positioned at different locations (e.g., upper section and side walls) of the optical path tube. This segmentation of the outlet function creates more uniform gas flow distribution throughout the tube, ensuring consistent gas velocity and pressure profiles that maintain stable flow characteristics.
Solution Approach 2:
Multiple outlet ports are combined to work together as a unified gas discharge system. The outlets are positioned and sized to complement each other, creating a coordinated flow pattern that achieves uniform gas distribution throughout the optical path tube while maintaining relatively simple individual outlet structures.
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 apparatus ensures smooth gas flow and reduces debris accumulation, thereby maintaining the intensity of EUV light extraction by preventing debris from adhering to optical components.
Implementation Method 1
a filter disposed in the optical path tube and configured to transmit light within at least one wavelength band selected from the light generated by the plasma
Implementation Method 2
the optical path tube is provided with at least one gas intake part configured to take gas into the optical path tube... the first outlet discharges the gas... and the at least one second outlet discharges the gas
Data Source
AI summary
A light source apparatus according to the present embodiment includes: an optical path tube configured to connect a space on a side at which a mirror is disposed and a space on a side at which a plasma forming area is disposed, the mirror being configured to extract light produced by plasma; and a filter disposed so as to cover the optical path tube and configured to transmit the light produced by the plasma. The optical path tube is provided with a gas intake part configured to take gas into the optical path tube, the gas intake part being provided on the side at which the plasma forming area is disposed relative to the filter. The optical path tube includes a first outlet and a second outlet configured to guide the gas outside of the optical path tube.