A method for fabricating a low frequency quartz resonator includes
metalizing a top-side of a quartz wafer with a metal etch stop,
depositing a first metal layer over the metal etch stop, patterning the
first metal layer to form a top electrode, bonding the quartz wafer to a
silicon handle, thinning the quartz wafer to a desired thickness,
depositing on a bottom-side of the quartz wafer a hard etch mask, etching
the quartz wafer to form a quartz area for the resonator and to form a
via through the quartz wafer, removing the hard etch mask without
removing the metal etch stop, forming on the bottom side of the quartz
wafer a bottom electrode for the low frequency quartz resonator,
depositing metal for a substrate bond pad onto a host substrate wafer,
bonding the quartz resonator to the substrate bond pad, and removing the
silicon handle.