Structurally supported thin film resonator and method of fabrication

A thin film resonator device, comprising:

• a substrate;
• a piezoelectric membrane disposed over the substrate;
• a first support structure defining a space over the substrate and supporting edges of the piezoelectric membrane such that the piezoelectric membrane is disposed over the space;
• a first electrode disposed on a bottom surface of the piezoelectric membrane;
• and
• at least a second electrode disposed over the piezoelectric membrane, portions of the space disposed under the first and second electrodes being an active resonator space;
• and
• an anti-flexing support structure disposed within the active resonator space.

A method of fabricating a thin film resonator device, comprising:

• forming a sacrificial layer over a semiconductor substrate;
• forming a first anti-flexing support structure in the sacrificial layer, the first anti-flexing support structure having a different etch selectivity from the sacrificial layer;
• forming an electrode over the sacrificial layer;
• forming a first piezoelectric membrane layer over the semiconductor substrate;
• etching a portion of the sacrificial layer under the first piezoelectric membrane layer to create a cavity under the first piezoelectric membrane layer such that the first anti-flexing support structure is disposed in the cavity to at least attenuate flexing of the first piezoelectric membrane layer.

A method of fabricating a thin film resonator device, comprising:

• forming a sacrificial layer over a semiconductor substrate;
• forming an anti-flexing support structure in the sacrificial layer, the anti-flexing support structure having a different etch selectivity from the sacrificial layer;
• forming a first electrode over the sacrificial layer;
• forming a piezoelectric membrane layer over the semiconductor substrate;
• forming at least one second electrode over the piezoelectric membrane layer;
• and
• etching a portion of the sacrificial layer under the piezoelectric membrane layer to create a cavity under the piezoelectric membrane layer such that the anti-flexing support structure is disposed in the cavity under both the first and second electrodes.

A thin film resonator device, comprising:

• a substrate;
• a piezoelectric membrane disposed over the substrate;
• a first support structure defining a space over the substrate and supporting edges of the piezoelectric membrane such that the piezoelectric membrane is disposed over the space;
• and
• an acoustical support structure disposed within the space to acoustically modify the piezoelectric membrane.

A method of fabricating a thin film resonator device, comprising:

• forming a sacrificial layer over a semiconductor substrate;
• forming an acoustic support structure in the sacrificial layer, the acoustic support structure having a different etch selectivity from the sacrificial layer;
• forming an electrode over the sacrificial layer;
• forming a piezoelectric membrane layer over the semiconductor substrate;
• etching a portion of the sacrificial layer under the piezoelectric membrane layer to create a cavity under the piezoelectric membrane layer such that the acoustical support structure is disposed in the cavity to acoustically modify the piezoelectric membrane layer.