F2 laser induced oxidation of inorganic material

Transparent SiO₂ thin films were selectively fabricated on Si wafer by 157 nm F₂ laser in N₂/O₂ gas atmosphere. The F₂ laser photochemically produced active O(¹D) atoms from O₂ molecules in the gas atmosphere; strong oxidation reaction could be induced to fabricate SiO₂ thin films only on the irradiated areas of Si wafer. The oxidation reaction was sensitive to the single pulse fluence of F₂ laser. The irradiated areas were swelled and the height was approximately 500-1000 nm at the 205-mJ/cm² single pulse fluence for 60 min laser irradiation. The fabricated thin films were analytically identified to be SiO₂ by the Fourier-transform IR spectroscopy. The SiO₂ thin films could be also removed by subsequent chemical etching to fabricate micro-holes 50 nm in depth on Si wafer for microfabrication.