We demonstrated a low-debris, efficient laser-produced plasma extreme ultraviolet (EUV) source by use of a regenerative liquid microjet target containing tin-dioxide (SnO2) nanoparticles. By using a low SnO2 concentration (6%) solution and dual laser pulses for the plasma control, we observed the EUV conversion efficiency of 1.2% with undetectable debris.

We measured debris characteristics of a tin (Sn) plasma produced by a 10-ns infrared Nd:YAG laser. A maximum kinetic energy of 7keV of tin ions was observed. Such suprathermal tin ions emitted from a solid planar target consisted of singly and doubly ionized tin ions. Both suprathermal ions and neutral fragments emitted from a target showed the angular distributions of cos4θ which were narrower than the 13.5-nm extreme ultraviolet (EUV) emission distribution of cos0.5θ. These measurements would give important information on debris mitigation for efficient EUV sources in the next generation lithography.

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We demonstrated a debris-free, efficient laser-produced plasma extreme ultraviolet (EUV) source by use of a regenerative liquid microjet target containing tin-dioxide (SnO 2 ) nano-particles. By using a low SnO 2 concentration (6%) solution and dual laser pulses for the plasma control, we observed the EUV conversion efficiency of 1.2% with undetectable debris.

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