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.