Fluorinated silica glass ablated with ArF excimer laser at low fluence

Amorphous SiO2 (a-SiO2) was formed by liquid-phase deposition (LPD) at room temperature. As a result of one shot of ArF excimer laser irradiation, LPD-formed a-SiO2 shows a threshold fluence for ablation of below than 200 mJ/cm2, which is much lower than the threshold fluence (∼1 J/cm2) of a-SiO2 formed by thermal oxidation of silicon. Raman scattering spectroscopy revealed that two sharp lines at 495 cm−1 and 606 cm−1, respectively, labeled D1 and D2, had disappeared, and the main band at 430 cm−1 was sharpened in LPD-formed a-SiO2. It is presumed that the fluorine broke the silica network, relaxing the Si–O–Si bond angle and dramatically reducing the threshold energy for ablation of a-SiO2.