Modification of sidewall roughness in silica deep etching and their influences on coupling loss in hybrid integration

The objective of this study was to find the relationship between process parameters and responses in deep silica etching for hybrid integration. The process parameters were the wafer temperature, oxygen addition, clamp material and process pressure. The responses to these parameters were sidewall roughness, profile of etched waveguide, the morphology of etched surface and critical dimension change. When the process parameters were varied, the change in responses could be interpreted by analyzing sidewall polymer thickness and selectivity. Polymer thickness and selectivity also have positive correlation. To investigate which parameter is dominant in determining the coupling efficiency between waveguide end facet and active device in application for hybrid integration, the propagation loss of waveguide with or without deep trenches were measured and analyzed.