In this article we present a study of deposition and etching techniques of germanium (Ge) and amorphous oxygen germanium (GeO_x) films, with the aim of using them as sacrificial layer in the fabrication of AlN-based MEMS by surface micromachining processes. The Ge and GeO_x layers were deposited by RF magnetron sputtering in Ar and Ar/O_2 atmospheres. By controlling the process parameters we were able to set the final composition of the GeOx films, which was assessed by FTIR measurements. We have studied the etch rates of GeO_x films with x ranging from 0 to 1 in H_2O_2 and H_2O_2/acid solutions. Depending on the etching temperature and the oxygen content in the layers, etch rates ranging from 0.2 to 2 μm/min were obtained. Nearly stoichiometric germanium oxide (GeO_2) was etched in pure H_2O at very high rate ( >1 μm/min at room temperature). We have also developed a chemomechanical polishing (CMP) process for the planarization of Ge and GeO_x. The influence of the slurries containing diverse powders (CeO_2, Al_2O_3) and chemical agents (NH_4OH, HCl), the different pads, and the various process parameters on the removal rate and the final sample topography has been studied. Finally, we have analysed the compatibility of the materials involved in the process flow with the processes of planarization and removal of the sacrificial layers.
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