A method of packaging a micro electromechanical structure is disclosed. The method comprises the steps of forming the structure on a substrate, depositing a sacrificial layer over the structure, patterning the sacrificial layer, depositing a porous layer over the patterned sacrificial layer, removing the patterned sacrificial layer through the porous layer, treating the porous layer with a plasma and depositing a capping layer over the plasma-treated porous layer. The plasma treatment step ensures that the capping layer material cannot enter the cavity formed by the removal of the sacrificial layer through the porous layer. A device formed by this method is also disclosed.