EUV Radiation Source Contamination Trap
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Solution Overview
Problem
The accumulation of contamination particles on reflective surfaces in lithographic apparatuses using extreme ultraviolet (EUV) radiation sources reduces the reflectivity of these surfaces, thereby decreasing the throughput of the apparatus.
Innovation Solution
A contamination trap comprising a plurality of foils is used to trap debris particles generated during plasma formation, with a heater to melt or evaporate trapped debris, and the foils are arranged to point towards the plasma formation site at shallow angles to effectively capture and remove contaminants before they reach the collector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a plasma source is used to generate EUV radiation, then the wavelength is shortened to achieve small features printing, but contamination particles are created that adhere to reflective surfaces and reduce reflectivity
Solution Approach 1:
A gas stream is introduced as an intermediary substance between the plasma source and the reflective surfaces. The gas flows through the vacuum chamber and carries contamination particles away from the optical path, preventing them from adhering to reflective surfaces while allowing EUV radiation to pass through to the substrate
Solution Approach 2:
The harmful contamination particles are extracted from the system by introducing a gas stream that selectively removes particles from the vacuum chamber environment. The gas flow extracts particles from the plasma region and transports them to a removal duct, separating the harmful by-products from the useful EUV radiation path
2Illumination intensity
If contamination particles accumulate on reflective surfaces, then the reflectivity of surfaces is reduced, but the throughput of the lithographic apparatus is decreased
Solution Approach 1:
A gas stream is introduced into the vacuum chamber before contamination particles can accumulate on reflective surfaces. This preliminary action of continuous gas flow prevents particle deposition by carrying particles away through a removal duct, maintaining reflectivity and avoiding throughput reduction
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 significantly reduces the likelihood of debris particles scattering back to the collector, enhancing the reflectivity and throughput of the lithographic apparatus by effectively trapping and removing contaminants from the EUV radiation source.
Implementation Method 1
a heater to heat the contamination trap to a temperature sufficient to melt debris that is trapped by the contamination trap, or to a temperature sufficient to evaporate debris that is trapped by the contamination trap
Implementation Method 2
a droplet of a fuel material is irradiated by a laser
Implementation Method 3
a radiation source configured to generate extreme ultraviolet radiation from a plasma
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A radiation source (SO) is configured to generate extreme ultraviolet radiation. The radiation source (SO) includes a plasma formation site (2) located at a position in which a fuel will be contacted by a beam of radiation (5) to form a plasma, an outlet (16) configured to allow gas to exit the radiation source (SO), and a contamination trap (23) at least partially- located inside the outlet (16). The contamination trap is configured to trap (23) debris particles that are generated with the formation of the plasma.