A method of fabricating an apparatus including a sealed cavity and an apparatus embodying the method is disclosed. To fabricate the apparatus, a device chip including a substrate and at least one circuit element on the substrate is fabricated. Also, a cap is fabricated. The cap is attached to the device chip using single phase metal alloy to achieve sealed cavity over the circuit element. The single phase metal alloy allows the cap to be diffusion bonded to the device chip at a higher diffusivity thus allowing diffusion at a lower temperature, lower pressure, shorter period, or a combination of these.