Ge doped film process in Waveguide application

摘要

Plasma Enhanced Chemical Vapour Deposition (PECVD) was used in the development of silica layers for use in planar waveguide applications. The addition of GeH_4 to silica was used to control the refractive index of core layers with index differences core-clad in the range of 0.2%-1.3%. High rate SiO_2 and Ge-doped SiO_2 films have been deposited on to 4" Si <100> wafers. The 'as deposited' and 'annealed' film properties have been compared, including film uniformity, RI, RI uniformity and stress have been compared. Ge-doped SiO_2 films up to 10 um thickness have been deposited and annealed for the above study. Refractive index uniformity of +- 0.0002 was achieved after annealing for 4" silicon wafers. The core layers were shown to be capable of producing optical losses of <0.1dB/cm when incorporated into a typical waveguide design.