EUV Radiation Source Nozzle Contamination Filter Assembly
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Solution Overview
Problem
Lithographic apparatuses using extreme ultraviolet (EUV) radiation sources face issues with contamination in the nozzle, leading to obstruction of fuel streams, affecting the trajectory and intensity of the radiation, which can result in suboptimal pattern printing and reduced operational duration.
Innovation Solution
A contamination filter assembly with a ceramic filter medium is integrated upstream of the nozzle, held in place by a clamping force provided by surrounding objects, preventing contamination from reaching the nozzle and ensuring consistent fuel flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nozzle is used to direct fuel droplets toward the plasma formation location, then the radiation source can generate EUV radiation, but contamination can be deposited on the internal surface of the nozzle, causing obstructions and affecting droplet trajectory and size
Solution Approach 1:
The patent extracts the filtering function from the nozzle system by introducing a separate contamination filter assembly upstream of the nozzle. This filter assembly removes contamination from the fuel stream before it reaches the nozzle, preventing deposition on the nozzle's internal surface while maintaining the nozzle's primary function of directing droplets accurately
Solution Approach 2:
The contamination filter assembly acts as an intermediary component between the fuel source and the nozzle. It mediates the fuel stream by removing contaminants before the fuel reaches the nozzle, thereby protecting the nozzle from contamination without interfering with the nozzle's droplet generation and direction functions
2Productivity
If the nozzle operates for extended periods, then productivity increases, but contamination accumulation leads to obstructions and reduced operational duration
Solution Approach 1:
The contamination filter assembly performs preliminary action by removing contamination from the fuel stream before it can enter and obstruct the nozzle. This preventive filtration allows the nozzle to operate for extended periods without contamination accumulation, thereby maintaining both high productivity and extended operational duration
3Reliability
If a filter assembly is added to prevent contamination, then nozzle reliability improves, but device complexity increases
Solution Approach 1:
The patent segments the fuel delivery system into distinct functional components: a contamination filter assembly for filtration, and a nozzle for droplet generation and direction. This segmentation allows each component to perform its specific function optimally without interfering with the other, improving reliability while keeping the added complexity localized to the filter assembly rather than the entire system
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 contamination from affecting the nozzle, maintaining the integrity of the fuel stream and radiation generation, enhancing the operational stability and longevity of the EUV radiation source.
Implementation Method 1
a laser configured to direct laser radiation at the stream at the plasma formation location to generate a radiation generating plasma
Implementation Method 2
a contamination filter assembly located in a fuel flow path of the radiation source, upstream of a nozzle outlet, wherein a filter medium of the contamination filter assembly is held in place within the contamination filter assembly by a clamping force
Data Source
AI summary
According to a first aspect of the present invention, there is provided a radiation source comprising: a reservoir configured to retain a volume of fuel; a nozzle, in fluid connection with the reservoir, and configured to direct a stream of fuel along a trajectory towards a plasma formation location; a laser configured to direct laser radiation at the stream at the plasma formation location to generate, in use, a radiation generating plasma; and a contamination filter assembly located in a fuel flow path of the radiation source, upstream of a nozzle outlet, a filter medium of that contamination filter assembly being held in place within the contamination filter assembly by a clamping force provided by one or more objects that at least partially surround the filter medium.