ナノ加工を目指したレーザプラズマ軟X線によるシリカガラスの非熱的アブレーションプロセスの探索

概要

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In this research, we examined process of silica ablation using laser plasma soft X-rays. We observed ionic and neutral species emitted from silica surfaces by irradiation with laser plasma soft X-rays. We mainly detected atomic species such as O+, Si+ and Si neutrals. Kinetic energies of detected ions are much higher than that of thermally evaporated atoms. There is an ablation threshold Fth at 60 mJ/cm2, and ablation rate R obeys a law R = 1/αln (F/Fth) beyond the threshold, where α is an effective absorption coefficient of 9.0×105 cm-1. The energy of laser plasma soft X-rays absorbed in silica surface at the threshold can be estimated to be 55 kJ/cm3, which is comparable with the binding energy of SiO2 of 76 kJ/cm3. These results suggest that the most of the bonds in silica glass are broken by absorption of soft X-ray, that several percent of the atoms are ionized, and that repulsive ions are emitted together with neutral atoms. The process enables us to fabricate nano structures.
社団法人電気学会の論文
2009-07-01