A method of formation of a microelectromechanical
system (MEMS)
resonator or filter which is compatible with integration with any analog, digital, or mixed-
signal integrated circuit (IC) process, after or concurrently with the formation of the
metal interconnect
layers in those processes, by virtue of its materials of composition,
processing steps, and temperature of fabrication is presented. The MEMS
resonator or filter incorporates a lower
metal level, which forms the electrodes of the MEMS
resonator or filter, that may be shared with any or none of the existing
metal interconnect levels on the IC. It further incorporates a resonating member that is comprised of at least one metal layer for
electrical connection and electrostatic actuation, and at least one
dielectric layer for structural purposes. The gap between the electrodes and the resonating member is created by the deposition and subsequent removal of a sacrificial layer comprised of a carbon-based material. The method of removal of the sacrificial material is by an
oxygen plasma or an anneal in an
oxygen containing ambient. A method of vacuum encapsulation of the MEMS resonator or filter is provided through means of a cavity containing the MEMS device, filled with additional sacrificial material, and sealed. Access vias are created through the membrane sealing the cavity; the sacrificial material is removed as stated previously, and the vias are re-sealed in a
vacuum coating process.