  In view of the integration of membrane resonators with more complex MEMS
structures, we developed a general fabrication procedure for circular shape
SiN$_x$ membranes using Deep Reactive Ion Etching (DRIE). Large area and
high-stress SiN$_x$ membranes were fabricated and used as optomechanical
resonators in a Michelson interferometer and in a Fabry-P\'erot cavity. The
measurements show that the fabrication process preserves both the optical
quality and the mechanical quality factor of the membrane.
