Transversely-excited film bulk acoustic resonators with molybdenum conductors

An acoustic resonator device comprising:

• a single-crystal piezoelectric plate having front and back surfaces, a portion of the piezoelectric plate forming a diaphragm;
• an interdigital transducer (IDT) formed on the front surface of the single-crystal piezoelectric plate such that interleaved fingers of the IDT are on the diaphragm, the piezoelectric plate and the IDT configured such that a radio frequency signal applied to the IDT excites a primary shear acoustic mode in the diaphragm, wherein the interleaved fingers of the IDT are substantially molybdenum, and wherein the diaphragm is contiguous with the piezoelectric plate around at least 50% of the IDT;
• a first front-side dielectric layer deposited between the fingers of the IDT;
• and
• a second front-side dielectric layer deposited over the first front-side dielectric layer.

A filter device, comprising:

• a single-crystal piezoelectric plate having front and back surfaces, portions of the single-crystal piezoelectric plate forming one or more diaphragms;
• a conductor pattern formed on the front surface, the conductor pattern including a plurality of interdigital transducers (IDTs) of a respective plurality of acoustic resonators, interleaved fingers of each of the plurality of IDTs disposed on one of the one or more diaphragms, the piezoelectric plate and all of the IDTs configured such that respective radio frequency signal applied to each IDT excite respective shear primary acoustic modes in the respective diaphragm, wherein the interleaved fingers of each of the IDTs are substantially molybdenum, and wherein each of the one or more diaphragms is contiguous with the piezoelectric plate around at least 50% of the IDT:
• a first front-side dielectric layer deposited between the fingers of at least some of the IDTs;
• and
• a second front-side dielectric layer deposited over the first front-side dielectric layer.