Piezoelectric MEMS device with thermal compensation from different material thicknesses

A piezoelectric microelectromechanical systems device comprising:

• a layer set sensitive to acoustic vibration, the layers including at least one piezoelectric layer and a two metal electrode layers having the same thickness, the layer set having an expected thermal stress deflection corresponding to a first thermal condition;
• a cavity having side walls supporting the layer set and providing space for acoustic vibration of the layer set into the cavity;
• and
• a compensation layer deposited directly onto one of the two metal electrode layers, the compensation layer having a compensation thicknesses configured to compensate for the expected thermal stress deformation, such that the combined layer set and compensation layer do not have the stress deflection under the first thermal condition.

A system for compensating for thermal stress m piezoelectric microelectromechanical systems devices at least partially spanning a cavity, the system comprising:

• at least one piezoelectric layer at least partially spanning a cavity such that it generates electrical signals when external forces cause the piezoelectric layer to vibrate with respect to the cavity;
• at least one electrode layer including a conductive metal positioned adjacent the piezoelectric layer and configured as an electrode to accept the electrical signals, the piezoelectric layer and electrode layer having an expected thermal stress tending to cause expected deflection even when external forces are not causing the piezoelectric layer to vibrate;
• and
• a compensation layer positioned adjacent at least one of the piezoelectric layer and the at least one electrode layer, deposited on the piezoelectric layer, and configured to counteract the expected deflection from the expected thermal stress.