ProcessesFabrication of ultra-high Q-value SiNx ring resonators

A ring resonator with a high Q value of 2.4 x 10⁵ has been fabricated despite its small ring radius of 100 μm. Compared to fused silica, SiNx has a high refractive index of about 2.0. However, the refractive index varies greatly depending on the ratio of Si to N, making it difficult to control. The liquid source CVD® system Model: PD-100ST is used to deposit SiNx films with an ideal refractive index of 1.99. In addition, the ICP etching system Model: RIE-400iP is used for SiNx anisotropic etching. The small diameter, high Q-value SiNx ring resonator is expected to improve the light extraction efficiency as a filter.

Photo courtesy of Yokoyama lab, Kyushu university