Rotational EUV Foil Trap Brazing and Cooling
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Solution Overview
Problem
The rotational type foil trap in EUV light source apparatuses faces issues with reduced EUV light transmission rate and shortened life duration due to thermal load, material degradation, and buckling caused by high input power, especially when using tin as the discharge raw material.
Innovation Solution
A rotational type foil trap configuration with foils brazed to a center support using gold brazing material, having a plate thickness between 0.2 mm and 0.5 mm, and a circular truncated cone-shaped center support, along with a dual channel heat exchange system to regulate temperature and prevent recrystallization, is employed to enhance durability and maintain light transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high input power is used to generate EUV light, then light output increases, but foil trap life duration decreases due to thermal load and material degradation
Solution Approach 1:
The patent applies parameter changes by optimizing the foil plate thickness to a specific range (0.2-0.5mm) to balance thermal resistance and mechanical strength, and by selecting gold as the brazing material with appropriate melting point and thermal conductivity parameters to withstand high input power conditions while extending foil trap life duration
Solution Approach 2:
The patent employs composite materials by combining different materials with complementary properties: foils made of molybdenum or tungsten (high melting point, low thermal expansion) brazed with gold (high ductility, good thermal conductivity), creating a composite structure that resists thermal load and material degradation at high input power
2Power
If high input power is used, then EUV light output increases, but light transmission rate decreases due to buckling
Solution Approach 1:
The patent changes the physical parameter of foil thickness to a specific range (0.2-0.5mm) that provides sufficient rigidity to prevent buckling under high input power conditions while maintaining adequate EUV light transmission, thus resolving the contradiction between power output and transmission rate reliability
Solution Approach 2:
The patent employs a circular truncated cone shape for the center support structure, which provides geometric stability and distributes thermal stress uniformly, preventing buckling of the foils while maintaining light transmission pathways
3Stability of the object's composition
If foil thickness is increased to prevent buckling, then structural stability improves, but EUV light transmission rate decreases
Solution Approach 1:
The patent optimizes the foil thickness parameter to a specific range (0.2-0.5mm) that achieves the optimal balance between structural stability (preventing buckling) and EUV light transmission rate, avoiding both too thin (buckling) and too thick (excessive absorption) conditions
4Ease of manufacture
If conventional joining methods are used, then manufacturing is simpler, but joint strength decreases under thermal load
Solution Approach 1:
The patent uses gold as a brazing material to join foils to the center support, creating a gold foil composite structure where the gold layer acts as a strong adhesive bond that withstands thermal expansion and mechanical stress, significantly improving joint strength compared to conventional mechanical fastening or welding methods
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 solution effectively prevents buckling and material degradation, ensuring a stable EUV light transmission rate and extending the life duration of the foil trap even at high input powers, while maintaining the foils within optimal temperature ranges to prevent contamination and recrystallization.
Implementation Method 1
the foils are brazed to a center support using gold brazing material
Implementation Method 2
a dual channel heat exchange system to regulate temperature
Implementation Method 3
foil trap that is capable of protecting a light condenser mirror or the like from a debris emitted from a high temperature plasma
Data Source
AI summary
Disclosed herein a rotational type foil trap that is capable of avoiding the transmission rate of the EUV light to be lowered even when the EUV light source operates with the high input power and also suppressing the temperature increase of the foil to attain a sufficient life duration. In the rotational type foil trap, one end of each of foils is inserted into each of a plurality of grooves provided on a side face of a center support, and the center support and the each of the foils are fixed together by brazing.