Surface processing by femtosecond EUV laser

We have demonstrated the surface processing by use of single and multiple EUV-FEL irradiations. Ablation threshold of silica glass against femtosecond EUV pulse is 20 times smaller than that of near-IR pulse. On the surface, damage free structures are found in interaction region. We have also investigated physical process of EUV-FEL induced ablation. Damage threshold of silicon increases with absorption coefficient. From the theoretical consideration based on the experimental result, the energy sink effect may help to avoid unwanted hydrodynamic motions. As the results, we conclude that the femtosecond EUV laser is a suitable tool for highly precise processing on materials.SACLA Users\u27 Meeting 201