Acoustic resonator filter with high thermal conductivity

A filter device comprising:

• a plurality of bulk acoustic resonators, wherein at least one bulk acoustic resonator comprises:
• a substrate;
• an intermediate layer disposed on the substrate and having a gas filled cavity that extends at least partially therein, the gas filled cavity having a heat dissipation gas having a thermal transport property greater than air;
• a piezoelectric layer having a portion that forms a diaphragm that is over the gas filled cavity;
• and
• an interdigital transducer (IDT) on a surface of the piezoelectric layer and having interleaved fingers on the diaphragm that have a thickness that is less than 0.5 times a thickness of the piezoelectric layer and greater than 0.2 times the thickness of the piezoelectric layer,
• wherein a bottom surface of the gas filled cavity faces the diaphragm and a cavity depth between the bottom surface and the piezoelectric layer is between 1.0 μm to 6.0 μm, and
• wherein the respective thicknesses and the cavity depth are measured in a direction substantially orthogonal to the surface of the piezoelectric layer.

A radio frequency module comprising:

• a filter device including a plurality bulk acoustic resonators connected in parallel;
• and
• a radio frequency circuit coupled to the filter device, the filter device and the radio frequency circuit being enclosed within a common package, wherein at least one of the plurality of bulk acoustic resonators of the filter device includes:
• a substrate;
• an intermediate layer disposed on the substrate and having a gas filled cavity that extends at least partially therein, the gas filled cavity having a heat dissipation gas having a thermal transport property greater than air;
• a piezoelectric layer having a portion that forms a diaphragm that is over the gas filled cavity;
• and
• an interdigital transducer (IDT) on a surface of the piezoelectric layer and having interleaved fingers on the diaphragm that have a thickness that is less than 0.5 times a thickness of the piezoelectric layer and greater than 0.2 times the thickness of the piezoelectric layer,
• wherein a bottom surface of the gas filled cavity faces the diaphragm and a cavity depth between the bottom surface and the piezoelectric layer is between 1.0 μm to 6.0 μm, and
• wherein the respective thicknesses and the cavity depth are measured in a direction substantially orthogonal to the surface of the piezoelectric layer.