Laser annealing of silicon dioxide (SiO₂) film formed by inductively coupled plasma enhanced chemical vapor deposition (ICPECVD) is studied for the fabrication of low loss silicon based waveguide. The influence of laser annealing on ICPECVD-deposited SiO₂ film is investigated. The surface roughness, refractive index, and etch rate of annealed samples are compared with those of SiO₂ film obtained by thermal oxidation. It is demonstrated that the performance of ICPECVD-deposited SiO₂ film can be significantly improved by laser annealing. Al₂O₃/SiO₂ waveguide has been fabricated on silicon substrate with the SiO₂ lower cladding formed by ICPECVD and laser annealing process, and its propagation loss is found to be comparable with that of the waveguide with thermally oxidized lower cladding.