HDP-CVD film for uppercladding application in optical waveguides

An optical waveguide is formed on a substrate by first depositing an undercladding layer over the substrate. At least one core is formed over the undercladding layer. An uppercladding layer is then formed over the cores with a high-density plasma process. Deposition of the uppercladding layer may proceed by flowing an oxygen-containing gas, such as O2, a silicon-containing gas, such as SiH4, and a fluorine-containing gas, such as SiF4, into a process chamber to produce a gaseous mixture. A high-density plasma, i.e. having a density of at least 1011 ions/cm3, is generated from the gaseous mixture and then used to deposit a fluorinated silicate glass layer.