Variable-Length Foil Trap for EUV Light Source Debris Capture
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Solution Overview
Problem
Current foil traps in EUV light source devices are inefficient in capturing debris from high-temperature plasma, leading to reduced reflectivity of EUV radiation on collector mirrors due to debris accumulation, and they obstruct a significant portion of the high-intensity EUV radiation with small angles of emission, thereby decreasing transmittance and intensity.
Innovation Solution
A novel foil trap design with foils extending radially from a main axis, where the length in the optical axis direction is shorter near the central axis than farther away, and the radiation emission side is concave, minimizing debris accumulation on collector mirrors while allowing more EUV radiation to pass through by adjusting the foil width and interval to maintain desired pressure and reduce blocked radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional foil trap with uniform foil length is used, then debris capture is effective, but a significant portion of high-intensity EUV radiation with small angles of emission is obstructed, decreasing transmittance
Solution Approach 1:
The foil trap employs foils with non-uniform length distribution, where the length in the optical axis direction varies with radial position. Foils near the central axis have shorter lengths while foils farther away have longer lengths, creating local variations in debris capture capability and radiation blocking to optimize both functions
Solution Approach 2:
The invention transitions from uniform foil structures to three-dimensional variable-length foil configurations, where foil length is differentiated across multiple spatial dimensions (radial and axial positions) to simultaneously address debris capture and radiation transmittance requirements
2Object-affected harmful factors
If foil length in optical axis direction is increased to improve debris capture, then more debris is captured, but more EUV radiation is blocked, decreasing intensity
Solution Approach 1:
Different regions of the foil trap have different foil lengths optimized for their specific functions: shorter foils near the axis minimize radiation blocking while longer foils at the periphery maximize debris capture, creating a gradient that balances energy loss and capture effectiveness
3Ease of manufacture
If uniform foil structure is used for simplicity, then manufacturing is easier, but debris accumulation on collector mirrors occurs due to insufficient capture efficiency
Solution Approach 1:
The foil trap is segmented into multiple foils of different lengths arranged radially, with each foil segment optimized for its specific radial position, creating a distributed capture system that improves reliability while maintaining manufacturability through modular construction
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 novel foil trap effectively captures debris, reduces kinetic energy, and enhances the transmittance and intensity of high-intensity EUV radiation with small angles of emission by optimizing foil placement and shape, improving the overall performance of EUV light source devices.
Implementation Method 1
Debris from the plasma is captured by a foil trap and kept from accumulating on a reflective surface of the mirror
Implementation Method 2
a high-voltage pulse is applied between first and second main electrodes and a high-temperature plasma is generated for irradiation of 13.5 nm wavelength EUV radiation
Implementation Method 3
The foil trap is shaped with a concave radiation emission side to improve the emissivity of the high-intensity EUV radiation
Data Source
Figure 1(a)(i)~1(c)(ii)
Figure 2(a)~2(c)
Figure 3(a)~3(c)
AI summary
An extreme ultraviolet (EUV) light source device and foil trap (15), the device including a vessel; an EUV radiating species supply means that feeds an extreme ultraviolet radiating species into the vessel; a discharge part with discharge electrodes (4,5) that heat and excite the EUV radiating species and generate a high-temperature plasma (8); a collector mirror (13) collecting EUV radiation emitted from the plasma; the foil trap installed between the discharge part and the mirror; an extractor part extracting the collected radiation; and an evacuation means exhausting and regulating pressure within the vessel. The foil trap includes foils extending radially from a main axis thereof to capture debris from the light source, while allowing the emitted radiation to pass through a region thereof to the mirror. A length of at least part of the foils in directions parallel to the main axis is shorter in positions close to the main axis than distant therefrom.