Low pressure encapsulated resonant structures were built with a cavity pressure of 1 mbar, obtained and measured for several structures bonded anodically to glass lids with different recess depths from 20.5 to 44 /spl mu/m. The same pressure has also been demonstrated for structures with integrated electrodes for electrostatic excitation and capacitive detection. No getter material or gas evacuation procedure was used. No leakage has been observed and measurements indicate 1 mbar and the same Q-values after six months storage. A theoretical model for the squeeze-film Q-factor taking into account both the pressure and the recess depth is also presented.