Submicron structures created on Ni thin film by submicron focusing of femtosecond EUV light pulses

Abstract

Abstract Using a newly developed submicron focusing system equipped with a large-aperture Wolter mirror with a precisely figured surface, we irradiate a Ni thin film coated on a silicon substrate with femtosecond extreme ultraviolet (EUV) laser pulses, generated as high-order harmonics of near-infrared femtosecond laser pulses. At the fluence of up to 100 mJ cm−2 at the sample surface, we show that the surface morphology can be modified with a submicron spatial resolution and that a protruding structure is formed when the fluence is 60–70 mJ cm−2, exhibiting a characteristic feature of the femtosecond EUV light processing of a thin metal surface.