VACUUM-ULTRAVIOLET PULSED-LASER DEPOSITION OF SILICON DIOXIDE THIN-FILMS

Vacuum-ultraviolet pulsed-laser deposition (PLD), using the 157-nm mol ecular fluorine laser, has been demonstrated to produce particulate-fr ee silica films from a fused silica target, in contrast with the 100-n m particulates found on films grown with the 193-nm ArF laser. XPS ana lysis has shown that films grown at low laser fluence (3-4 J cm(-2)) i n 2 X 10(-4) Torr of dry air have significantly improved stoichiometry (SiO1.9), relative to films grown in vacuum (SiO1.75). Additionally, for films grown in vacuum, low ablation fluences (3-4 J cm(-2)) produc ed films with higher oxygen content (SiO1.75) than high ablation fluen ces (>10 J cm(-2) peak fluence - SiO1.65) FTIR has shown that the char acteristic Si-O-Si asymmetric stretching mode (ASM) absorption peak in the best films grown to date lies at similar to 1050 cm(-1), with a w idth of 90 cm(-1) (FWHM), as compared with the 1060-1080 cm(-1) positi on and 70-75 cm(-1) width in a high quality thermal oxide. Process opt imization and doping with optically-active and -passive ions will perm it low-temperature growth of planar optical waveguides for use in opti cal integrated circuits. (C) 1998 Elsevier Science B.V.