SULFUR HEXAFLUORIDE FILLED SURFACE ACOUSTIC WAVE (SAW) THIN-FILM ACOUSTIC PACKAGE (TFAP) DOMES
Certain aspects of the present disclosure provide a surface acoustic wave (SAW) device. The SAW device may include a piezoelectric layer, and an interdigital transducer (IDT) disposed above the piezoelectric layer. The IDT may include a plurality of fingers. A cap layer may be disposed above the IDT. A cavity may be formed between the IDT and the cap layer. A material such as sulfur hexafluoride (SF 6 ) may be disposed above and between the plurality of fingers of the IDT within the cavity.
1 . A surface acoustic wave (SAW) device comprising:
a piezoelectric layer;
an interdigital transducer (IDT) disposed above the piezoelectric layer, wherein the IDT comprises a plurality of fingers;
a cap layer disposed above the IDT, wherein a cavity is formed between the IDT and the cap layer; and
a material having a dielectric strength value exceeding a first threshold disposed above and between the plurality of fingers of the IDT within the cavity.
2 . The SAW device of claim 1 , wherein:
the dielectric strength value is below a second threshold; and
a value of the second threshold is higher than a value of the first threshold.
3 . The SAW device of claim 1 , wherein the material comprises sulfur hexafluoride (SF 6 ).
4 . The SAW device of claim 1 , wherein the cap layer comprises silicon dioxide (SiO 2 ).
5 . The SAW device of claim 1 , wherein the cap layer comprises silicon nitride (Si3N4).
6 . The SAW device of claim 1 , further comprising a passivation layer disposed above the IDT, wherein the passivation layer comprises silicon nitride (Si3N4) or aluminum oxide (Al 2 O 3 ).
7 . The SAW device of claim 1 , further comprising a passivation layer disposed below the cap layer, wherein the passivation layer comprises silicon nitride (Si3N4) or aluminum oxide (Al 2 O 3 ).
8 . The SAW device of claim 1 , further comprising a sealing layer disposed above the cap layer and a portion of the piezoelectric layer, and wherein the sealing layer comprises a polymer material.
9 . The SAW device of claim 8 , further comprising a reinforcement layer disposed above the sealing layer, wherein the reinforcement layer comprises silicon nitride (Si3N4).
10 . A plurality of resonators forming a filter circuit, wherein the SAW device of claim 1 is a resonator in the plurality of resonators.
11 . A wireless device comprising:
a radio frequency (RF) circuit; and
a surface acoustic wave (SAW) device coupled to the RF circuit, the SAW device comprising:
a piezoelectric layer;
an interdigital transducer (IDT) disposed above the piezoelectric layer, wherein the IDT comprises a plurality of fingers;
a cap layer is disposed above the IDT, wherein a cavity is formed between the IDT and the cap layer; and
a material having a dielectric strength value exceeding a first threshold is disposed above and between the plurality of fingers of the IDT within the cavity.
12 . The wireless device of claim 11 , wherein the RF circuit comprises a transmit path and a receive path and wherein the SAW device forms a portion of a duplexer coupled to an output of the transmit path and to an input of the receive path.
13 . The wireless device of claim 11 , wherein:
the RF circuit comprises a low-noise amplifier (LNA); and
the SAW device is coupled to an output of the LNA.
14 . A method of fabricating a surface acoustic wave (SAW) device, the method comprising:
forming an interdigital transducer (IDT) above a piezoelectric layer, wherein the IDT comprises a plurality of fingers; and
forming a cap layer above the IDT such that a cavity is formed between the IDT and the cap layer, wherein a material having a dielectric strength value exceeding a first threshold is disposed above and between the plurality of fingers of the IDT within the cavity.
15 . The method of claim 14 , wherein:
the dielectric strength value is below a second threshold; and
a value of the second threshold is higher than a value of the first threshold.
16 . The method of claim 14 , wherein the material comprises sulfur hexafluoride (SF 6 ).
17 . The method of claim 14 , wherein the cap layer comprises silicon dioxide (SiO 2 ).
18 . The method of claim 14 , wherein the cap layer comprises silicon nitride (Si3N4).
19 . The method of claim 14 , further comprising forming a sealing layer above the cap layer and a portion of the piezoelectric layer.
20 . The method of claim 19 , wherein the sealing layer comprises a polymer material.