Si/sub 3/N/sub 4/ film etching to form fine tapered structures for photonics applications

Dry plasma etch process was optimized to form fine SiN waveguide tapered structures with acceptable profile. Best results were obtained by achieving etch optimization of individual layers present in the stack. Using different plasma gas combinations for Si/sub 3/N/sub 4/ etching to achieve required etch depth and selectivity was found to be promising approach to form fine structures. By reducing etch bias and obtaining vertical profile may help lower the coupling loss through these fine structures.