Smoothing of microfabricated silicon features by thermal annealing in reducing or inert atmospheres

In this work, high-temperature annealing of reactive ion etched silicon microstructures in H2 and Ar gases is studied. Three types of structural features were etched with four different masks into lang100rang-oriented silicon wafers. Scanning electron microscope and atomic force microscope (AFM) results show that when smoothing due to surface diffusion and desorption of silicon is taking place in both the argon and hydrogen gas environments, the three types of features respond differently to the treatments. The surface diffusion was observed to be strongly dependent on temperature in argon, whereas the transport was more linear and controllable in the hydrogen gas environment. For hydrogen, AFM studies were performed to observe the details of the smoothing process. Finally, some potential applications of these transport phenomena are discussed.