Transversely-excited film bulk acoustic resonator package and method

A method of fabricating an acoustic resonator device comprising:

• fabricating an acoustic resonator chip comprising:
• a substrate having front and back surfaces, at least two cavities formed in the front surface;
• a piezoelectric plate having front and back surfaces, the back surface attached to the front surface of the substrate except for portions of the piezoelectric plate that form at least two diaphragms spanning the at least two cavities;
• and
• a first conductor pattern formed as one or more conductor layers on the front surface of the piezoelectric plate, the first conductor pattern comprising:
• at least two interdigitated transducers (IDTs), interleaved fingers of each of the IDTs on one of the diaphragms;
• and
• a first plurality of contact pads;
• fabricating an interposer having a second plurality of contact pads on a back surface of the interposer;
• and
• forming respective conductive balls on either the first plurality of contact pads or the second plurality of contact pads;
• and
• bonding each of the first plurality of contact pads to a respective pad of the second plurality of contact pads using the respective conductive ball,
• wherein the piezoelectric plate and the at least two IDTs are configured such that a respective radio frequency signal applied to each IDT excites a bulk shear acoustic wave within the respective diaphragm.

A method of fabricating a filter device, comprising:

• fabricating an acoustic resonator chip comprising:
• a substrate;
• a piezoelectric plate having a back surface attached to the substrate;
• and
• a conductor pattern formed on a front surface of the piezoelectric plate, the conductor pattern comprising:
• a plurality of interdigital transducers (IDTs) of a respective plurality of acoustic resonators, interleaved fingers of each of the plurality of IDTs on respective portions of the piezoelectric plate suspended over one or more cavities formed in the substrate;
• conductors to connect the plurality of acoustic resonators in a ladder filter circuit;
• and
• a first plurality of contact pads;
• fabricating an interposer comprising a second plurality of contact pads on an interposer back surface;
• forming respective conductive balls on either the first plurality of contact pads or the second plurality of contact pads;
• and
• bonding each of the first plurality of contact pads to a respective pad of the second plurality of contact pads using the respective conductive ball.