Spectral Unraveling of EUV Lithography Light Sources

The EUV light sources that power the most advanced lithography machines are likely the most complex light sources in existence. Detailed knowledge of the light is needed to increase efficiency, optimize imaging performance and design materials that can withstand the plasma environment inside the lithography machines.

In a collaboration with ARCNL and ASML, supported by TKI - Holland High Tech, researchers at University Twente built a unique spectrometer that can measure the source spectrum over the entire range from EUV to visible wavelengths.

The EUV source spectrum spans over four octaves and is dominated by the small band around 13.5 nm for which the light source is designed. However, the light at other wavelengths, particularly between approximately 100 and 200 nm, will influence plasma conditions in the scanner and provides detailed information on the physics that plays a role in the EUV source and transport of the light.

To study future EUV source configurations and the spectral background, test setups with different types of EUV sources are in operation at TNO, ARCNL and ASML. Towards the end of this project researchers were able to measure and quantitatively compare the sources at the different sites. This provides new insights into the physics surrounding laser produced plasma sources and further strengthens the collaboration between these Dutch research institutes.