ICP-CVD Silicon-Rich Silicon Nitride for Supercontinuum Generation

Nonlinear on-chip applications require materials with high linear and nonlinear refractive indices combined with low or negligible two photon absorption. Thanks to its extremely low attenuation, the stoichiometric silicon nitride is currently the most studied material. However, several alternative materials have appeared and benefit from higher nonlinearity: $\text{Ta}_{2}\mathrm{O}_{5}$ [1], $\text{TiO}_{2}$ [2] and the non-stoichiometric silicon nitride which can be richer in nitrogen [3] or in silicon [4]. This material can be processed by different chemical vapor deposition (CVD) based approaches: Low Pressure LP-CVD [5], Plasma Enhanced PE-CVD [2] or Inductively Coupled Plasma ICP-CVD [7]. In our facilities, we use the latest to get thin films of non-stoichiometric SiN with indices ranging from 1.7 (nitrogen rich) to more than 3 (ultra-silicon-rich).