Silicon profile transformation and sidewall roughness reduction using hydrogen annealing

We report on a comprehensive study of the 3D profile transformation process for microstructures on silicon-on-insulator (SOI) substrates. Using hydrogen annealing, single crystalline microspheres (1 /spl mu/m radius), micropillars, and circular cantilever beams have been successfully demonstrated. The annealed Si exhibits a surface roughness of 0.26 nm. A theoretical model is presented for the mass transport process, and the parametric dependence on temperature and pressure is characterized. We have used this process to fabricate submicrometer single mode optical waveguides on SOI and achieved a very low optical loss of 0.2 cm/sup -1/.