Influence of hydrogen on SiO₂ thick film deposited by PECVD and FHD for silica optical waveguide

Abstract

Abstract Silicon dioxide (SiO 2 ) thick films have been deposited by plasma enhanced chemical vapor deposition (PECVD) and flame hydrolysis deposition (FHD). PECVD SiO 2 films were obtained at low temperatures (<350 °C) by the decomposition of the appropriate mixture of (SiH 4 +N 2 O) gases under suitable rf power and N 2 O/SiH 4 ratio. For low N 2 O/SiH 4 ratio, a refractive index(n) value close to 1.50 is obtained. The deposition rate increased with the increase of rf power. FHD SiO 2 films were produced by the flame hydrolysis reaction of halide materials such as SiCl 4 , POCl 3 and BCl 3 in an oxy‐hydrogen torch. The porous SiO 2 layer, under the POCl 3 /BCl 3 ratio deposition condition, has to be consolidated by annealing at around 1300 °C.