Thin silicon nitride nanomembranes are attracting growing attention following a novel fabrication method which consists in patterning them with a phononic crystal. In engineering the vibrational mode profile, the dominant mechanisms of loss, radiation loss and intrinsic material loss, are simultaneously addressed and mitigated. The fabrication method employed by the optomechanics group at the Laboratoire Kastler Brossel is here presented, only employing basic lithography techniques and wet etching processes.
