Substrate processing and membrane release of transversely-excited film bulk acoustic resonator using a sacrificial tub
AssigneeResonant Inc.
InventorsAlbert Cardona, Douglas Jachowski, Chris O'Brien
Life of this patent
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Abstract
An acoustic resonator device is formed using a sacrificial layer and a front side etched cavity by forming a recess in a silicon substrate with a trap-rich top layer and filling the recess with sacrificial silicon nitride. A bonding oxide (BOX) layer is formed over the trap-rich layer and the sacrificial silicon nitride filled recess and a piezoelectric plate is bonded to the BOX layer. The sacrificial silicon nitride is then removed to form a cavity by using an etchant introduced through holes in the piezoelectric plate and BOX layer without removing the BOX layer from over the cavity.
Claims20
A method of forming a filter device using a sacrificial layer and a front side etched cavity comprising:
- forming a recess in a silicon substrate with a trap-rich top layer;
- filling the recess with sacrificial silicon nitride;
- forming a bonding oxide (BOX) layer over the trap-rich layer and the sacrificial silicon nitride filled recess;
- bonding a piezoelectric plate to the BOX layer;
- and
- removing the sacrificial silicon nitride using an etchant introduced through holes in the piezoelectric plate and BOX layer to form a cavity without removing the BOX layer from over the cavity.
A method of forming a filter device using a sacrificial layer and a front side etched cavity comprising:
- forming a recess in a silicon substrate;
- filling the recess with a sacrificial layer;
- forming a bonding oxide (BOX) layer over the substrate and the sacrificial layer filled in the recess;
- bonding a piezoelectric plate to the BOX layer;
- removing the sacrificial layer using an etchant introduced through holes in the piezoelectric plate and BOX layer to form a cavity without removing the BOX layer from over the cavity;
- and
- forming a frontside dielectric over the plate.
A method of forming a filter device using a sacrificial layer and a front side etched cavity comprising:
- forming a recess in a silicon substrate;
- filling the recess with a sacrificial layer;
- forming a bonding oxide (BOX) layer over the substrate and on the sacrificial layer in the recess;
- bonding a piezoelectric plate to the BOX layer;
- forming a conductor pattern on a front surface of the piezoelectric plate, wherein the conductor pattern includes an interdigital transducer (IDT) with interleaved fingers disposed over the recess;
- removing the sacrificial layer using an etchant introduced through holes in the piezoelectric plate and BOX layer to form a cavity where the sacrificial layer was removed without removing the BOX layer from over the cavity;
- and
- forming a frontside dielectric over the plate.
Dependencies are inferred from the claim text.