July 15, 2011 — Lithography light source maker Gigaphoton Inc. verified its original technology for mitigating debris with magnetic fields for laser-produced plasma (LPP) light sources, clearing a hurdle for mass-production use.
Gigaphoton has been developing LPP light sources for EUV lithography since 2002, aiming for higher output and better CoO. Gigaphoton has now proven in production-level light sources that its debris mitigation with magnetic fields technology removes 93% of debris. Also read: The physics behind Gigaphoton’s EUV source
LPP light sources allow radiation by a CO2 laser of the Sn target (droplets) to cause EUV emission. Sn debris, such as Sn fragments and Sn atoms, land on the collector mirror and Sn ions damage the mirror’s multi-layer film, lowering reflectance. The debris mitigation technology with magnetic fields can reduce tin (Sn) deposited on the collector mirror and prevent damage to the mirror’s multi-layer film.
Gigaphoton’s magnetic debris mitigation technology combines the pre-pulse generated by a solid-state laser and the main pulse generated by a CO2 laser to suppress Sn fragment and neutral Sn atom generation, ionizing most of the Sn in each droplet. Ionized Sn is guided to the Sn catcher magnetically and removed.
During the verification experiment, the main pulse of the CO2 laser radiated each 20