Abstract: Titania-silica thin films were prepared by a Sol-gel method. The etched ability of the thin films in dilute HF solution was studied. The
film heat-treated at 800℃, reduced etch rate by a factor of almost 1000 compared with that of the film heat-treated at 200℃.
The large difference between the etch rates of densified and undensified films can be used to produce channel waveguide structures by laser scanning on the films. The difference
of the etch rates can be explained by XRD and FT-IR spectrum, and micro Raman spectrum reveals that the crystallization in the region of
laser scanning has a normal distribution.

Key words: film, structure, laser scanning, chemical etch, micro Raman spectrum