Waveguide Roughness Measuring Metrology with Confocal Laser Scanning Microscope (CLSM)

Sidewall-roughness Scattering loss is one of the important parameters affecting waveguide performance. We use the numerical simulation to find the correspondence between roughness and scattering coefficient. This paper is mainly focused on the limitation analyses for the sidewall roughness (SWR) measurements of microstructures with a confocal laser scanning microscope (CLSM). The CLSM can be used to measure the SWR of a large area without damaging the wafer. The CLSM-metrology is investigated to overcome the intrinsic limitations of SEM-metrology with the average value over a large region. Finally, with the average SWR values of 90-110nm are obtained with CLSM that are agreeable with the measured SWR values of 88-105nm obtained with a scanning electron microscope (SEM).