Silicon nitride for nonlinear optics applications in the telecommunications C-band deposited by ECR-CVD

Silicon nitride films deposited by low-pressure electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-CVD) at room temperature are proposed for nonlinear optics applications in the telecommunications C-band. Numerical simulations were performed to determine the relationship between refractive index and the waveguide minimum size in order to have the zero dispersion point at 1.55 μm. Silicon nitride films with large thickness, low roughness and high refractive index were obtained by varying deposition parameters, such as gas pressure (4-6 mTorr) and Si/N ratio. The Si-rich silicon nitride film developed for nonlinear applications with refractive index of 2, high deposition rate, low hydrogen concentration and low roughness was used for fabrication of nonlinear microring resonators. Using the deposition process at low temperature, the stress limitation in thick silicon nitride films was eliminated.