PROCESS FLOW WITH PRE-BIASED MASK AND WET ETCHING FOR SMOOTH SIDEWALLS IN SILICON NITRIDE WAVEGUIDES

Aspects of the present disclosure are directed to process flow to fabricate a waveguide structure with a silicon nitride core having atomic-level smooth sidewalls achieved by wet etching instead of the conventional dry etching process. A mask is pre-biased to account for lateral etching during the wet-etching steps.