Extreme ultraviolet (EUV) lithography is being introduced in line with process miniaturization. EUV light with a wavelength of 13.5 nm is produced by evaporating molten tin droplets with a CO2 gas laser and plasmaizing them.

As a byproduct of light source creation, tin debris adheres to the reflective optics of the EUV light source and collects the EUV light emitted from the plasma. A thickness of about 1 nm (just a few atomic layers) of deposited tin can reduce the reflectivity of the collector mirror by as much as 10%, reducing lithography throughput.

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Hydrogen plasma (combined with a magnetic field) chemically removes tin as stannic gas (SnH4), which can be efficiently exhausted from the vacuum chamber to prevent tin re-deposition.

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To make this tin removal as time-efficient as possible, Aston provides fast, actionable, and accurate data from in-situ measurements to accurately determine the endpoint of the process. This reduces the consumption of high-purity hydrogen and the time required for tin removal, allowing more time to work with expensive lithography equipment.

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To learn more about Aston, download the application brief below to see how Aston supports industry-leading sensitivity and improved endpoint detection.